Snoop appears, as if by magic, in a puff of his own smoke. The rapper, actor, gangster and stoner extraordinaire has reinvented himself as a reggae-singing messenger of hope. Snoop Dogg is dead, long live Snoop Lion.

We meet in his management office in Los Angeles, an enormous warehouse dedicated to all things Snoop. On the walls are huge Snoop posters, to the left is the Snoop television studio, where two near-naked women are chatting, and to my right is an old-fashioned video with a stack of Snoop VHSs lined up alongside it.

He slopes in, long and loping, in a white T-shirt, dark jeans and jacket, trainers and shades, blingtastic lion medallion hanging down his chest, patchy Rasta beard, and surprisingly beautiful. He shakes hands, asks one of his homies why there is no oil in his ganja pipe, flicks on the huge flatscreen TV in front of us and starts watching a bit of Snoop history. He is instantly engrossed. No sooner has he sat down than he is up and dancing. "'Baby if you want me…'"

Snoop has just made a documentary that charts his path from gun-toting gangsta-rapper to the peace-and-love Rastafarian who claims to have been reincarnated (the name of both the film and his new album). I tell him I like the film. "Thank you, man. It's from the heart and soul." He talks about how he has changed as a man, a husband, a father of three. "When you allow evolution to happen, that's when it becomes the greatest thing it could possibly be." He's still staring at the screen and comes to a sudden stop. "Who is that? Is that Rachel from BET [Black Entertainment Television]? Well, whoever she is, she fine as a motherfucker. She pregnant, too. That is Rachel! You bitch, you. Jamaican Rastafari. Yeah, man."

Snoop Lion still has a fair bit of the Dogg in him. But then Snoop Doggy Dogg, as he was first known, was never afraid of embracing his contradictions. He emerged in 1993 with the hugely successful album Doggystyle, and set the pattern for 20 years of guns, gangsters and misogyny. His voice was rich and seductive. His raps were X-rated, yet the kids loved him. He wrote about pimping and dealing on the streets of underclass black America, yet the white middle classes adored him (even the upper classes: Princes William and Harry are fans). Despite the bleak violence he portrayed, there was an innocence to his world – the video to one of his early hits, Gin & Juice, showed partying kids panicking as the parents arrive back early. Only Snoop could dare to write Ain't No Fun (If The Homies Can't Have None), which critics have described as a paean to gang rape, as a love song "for the ladies". He worships the free market, having endorsed everything from Pepsi Max to Norton Anti-Virus Software, and is now worth an estimated $110m. Yet he is a staunch Democrat.

Snoop is one of rap's great survivors. Twenty years on, he is still successful when many of his contemporaries are dead. As a young man he was in and out of prison for drug dealing; in 1993 he was charged with accessory to murder, though he was eventually cleared; a decade ago he combined his successful recording career with pimping (until it put too much stress on his marriage) and in 2006 he was barred from entering the UK after he and his entourage went tonto at Heathrow airport. Yet there is something endearing about Snoop – after all, Calvin Cordozar Broadus Jr originally got his nickname because he looked like Snoopy and he still bears a passing resemblance. In 2006, Rolling Stone magazine featured him on its cover under the headline "America's most lovable pimp".

The metamorphosis into Snoop Lion seems pretty radical. What brought about the change? "I wanted to make songs about the life I'm living now as a father and as a 41-year-old man, as opposed to always talking about my childhood and my upbringing."

Couldn't he have done that as a rapper? "I don't think it could have worked through rap because of my branding." Like many rappers, Snoop is a good businessman. "I branded Snoop Dogg to be what he is, and it's too late to change the brand." What is that brand? "Gangsta. West coast, from the hood. Speaking for the lost generation – the gangstas, the drug dealers. And I did it 21 years straight, faithfully, till I couldn't do it any more."

He couldn't do it any more, he says, for the simple reason that it would be dishonest to – this hasn't been his life for a long time. "Finally I'm able to say I'm comfortable with doing what I do. And I love doing it. And I'm going to keep doing it. If I don't make another rap record for the next year or two or three, or however long it takes, it don't bother me because I'm trying to make music that feels good."

But, typical Snoop, he makes no bones about the fact that Lion is just an extension of the Dogg brand. The two will happily coexist. Sometimes he will tour as Snoop Dogg, sometimes as Snoop Lion, sometimes as a bit of both.

He offers me his spliff. Though to call it a spliff is an insult really – it's a professionally rolled cigar of pure ganja. An object of beauty, I say.

"You think so?" he says sweetly.

Have you got your own spliff factory?

"I got a couple of homies that do it. We ain't got no factory. But we move like a machine." He speaks slowly, sensually.

I haven't smoked dope for 20-odd years, but to refuse Snoop seems churlish. "You gotta have one hit," he says. I tell him I might make an exception. I inhale. "Welcome to California," he says. It tastes gorgeous – mellow, sweet, lovely. So I have another go. Woosh! Within seconds my head's spinning, I'm spluttering and talking in a falsetto. He grins.

I tell Snoop some of his early videos remind me of the television series Happy Days. He turns away from the giant flatscreen. "The Fonz! And Chachi! That's how life was! We lived like that. We were gangstas, but we were having fun." But those days of innocence didn't last long. By the mid-90s there was civil war between the west and east coast, and rap was becoming a blood bath. By March 1997, two of the greatest rappers – Tupac Shakur and Biggie Smalls – had been killed within six months of each other.

Snoop with the late rapper Tupac Shakur. Photograph: Sipa Press/Rex Features

How did things go so wrong? "Drugs came into our neighbourhood," he says. "And once the drugs became part of our life, guns were introduced to us, and once you introduce the guns and drugs, it becomes jealousy and protect your neighbourhood, and before you know it somebody gets shot at, and you do shooting. And it just goes on and on. And once somebody gets killed it seems like it's never gonna stop because we are trying to even it out. Homies was getting shot every other night, then one of my family members got killed. And when that happens it's a horrible feeling. You never want to feel that."

Calvin Cordozar Broadus Jr was born in Long Beach, California, in 1971. He took his step-father's name – when he was three months old his biological father walked out on the family, though they have since been reconciled. He sang and played piano in the church choir, but gave up the piano when he finished second in a contest. "I was like, I don't want to do this no more, I don't like being second." Was he competitive as a kid? "I hate losing. Even to this day, I'm a sore loser."

By his teens, Snoop was a member of the Rollin' 20s Crips, a notorious Long Beach gang. The funny thing is, he says, people now expect him to look back on his early life with regret, and they couldn't be more wrong. "I wanted to be a gangsta my whole life. Even when I came home from church, we'd see all the gangstas and that was more appealing to me, so when I finally got a chance to live it, to do it, I rapped about it. I was like, I'm going to do it like nobody's ever done it before because my shit is going to be 100% authentic because I come from it and I am it." Being a gangster was a way of transcending poverty; then rapping about life as a gangster became a way of transcending the gangs.

Did being a gangster live up to expectations? "Well hell, yeah, I loved every minute of it. When you ask for it, you've got to be ready to receive it. I knew the job was dangerous when I took it." Was he a good gangster? For once, he pauses. "I don't think there are no good ones," he eventually says.

How surprised is he today to see 41? "Mmm. I did some things that could have cut my days short."

Did he think he would go down when he was charged with accessory to murder? "I did. I thought I was going to go down for that. Every day of my life I thought it was my last day on the streets. When you're in court, you have no real sense of vibe and what is going to be until they read it off. You're in there trying to be on your best behaviour, they're tearing your character down, they're bringing up pictures of you with guns, and the kind of person you was when you was that person, and saying you're still that person, and you're on that witness stand and you can't even say anything."

After he was acquitted, he released his second album, Tha DoggFather, which led to accusations that he was glorying in his gangster status: the intro started with a commentary that he was now more famous for his murder charge than his music. Twenty years on, he has written No Guns Allowed, which he sings with his 13-year-old daughter Cori B. Is it strange for him to be singing an anti-gun song? No, he says, it makes perfect sense. "We keep hearing about schools getting shot up, venues being shot up, public places being shot up, and we have to address that. Who better to do it than me because I come from the gangsta lifestyle, carrying a gun every day of the week lifestyle?"

He talks about the other ways Rastafarianism has changed him. "I used to answer hate with hate. Like if you hate me, I hate you more. But now I answer hate with love." What about your attitude to women? Was there hate in the lyrics of early songs, the bitches and the hos? "Yeah, because I was making music for me, speaking from my perspective. I was taught that a bitch is a ho and a ho was a bitch, so my music represented that, until I got to the point where I wanted to show love and appreciation for the woman."

He's staring at the screen again. "She is fine. She got tush. You know when they got body? If you go to Taco Bell, right, order something to eat, and the bitch looks good in them slacks, imagine what she going to look like when you put her in a skirt." I'm beginning to feel as if I'm in a Tarantino movie.

The more Snoop smokes and the more he focuses on the screen, the easier his words come. Blimey, I say, how many of these do you smoke a day? "Today is a bad day." Does that mean lots? "That means I'm going low. Because I keep getting asked questions so I got to make sure I'm on point. On a bad day 5-10. On a good day 25-30."

Is it true that he smokes with his older son, Corde, 18? "Yeah, he deserve it." Isn't he a good sportsman? "No. He's a good smoker. His brother's a good sportsman. He took on my smoke side, his brother took on my sport side." He turns back to the TV. "Hey, that's Sheila Frazier. Super Fly's girl. Sheila Frazier! Show that bathtub scene!"

As he talks, I notice the semi-clad girls at the back of the room. "Snoop," I say, "the ladies here don't have many clothes on."

He bursts out laughing. "The ladies here don't have many clothes on!" he shouts to his homies in a fey English accent. "That's what the interviewer said! I'm loving it! They're my weather girls. They work for my news network." Snoop's network, GGN, records its shows from here.

It's amazing how much you get away with, I say. I tell him about an article by the feminist writer Julie Bindel, in which she admitted that, despite despising everything Snoop stood for, she adored him. Why does she forgive you? He turns away from the TV. Now this subject really does interest him. "It's not even forgiving, it's you connected to me." He talks about me to illustrate his point: "I might not like the way you dress, but I like the way you talk, so I'll fuck with you." Thanks, I say. I had picked out my jeans, striped top and brothel creepers especially. "You know, for the benefit of the doubt, your outfit ain't really together, but your conversation is sharp. And that's what it is about me. Sometimes it ain't what I say, it's how I say it. So she may appreciate the delivery more than the particular words. It may tickle her fancy. So I'm going to shoot her a shout-out. 'Julie Bindel, I just want to let you know that we really love and appreciate everything about you. And what I want to know is how could you hate my lyrics so much and love me as a person? Please let me know. I would love to know so that way we can get a better connection. Appreciate you.'" The words drip from his tongue.

Ziggy Marley, Robbie Marley, Snoop and Rohan Marley at the Marley film premiere in LA. Photograph: Jim Smeal/BEI/Rex Features

One of the many surprises about Snoop is that he has been with his wife, Shante Taylor, since they were childhood sweethearts – though, it has to be said, not exclusively. He filed for divorce in 2004, but they renewed their wedding vows in 2008 on his reality show, Snoop Dogg's Father Hood. Didn't she go berserk when he wrote all those songs about bitches and hos? "No, she played her position. At the time she was my girlfriend and she became my wife. I made her my wife because I loved her and I loved everything about what she stood for, as far as being there for me, having my kids, and just being a down-ass woman. And when I say I'm going to marry you that means you gotta take the good, the bad and the ugly. And she took everything. She took it when I was doing it this way, doing it that way. She knew."

I ask if that is a reference to his pimping days, when he was already a superstar. Now he gives me a filthy look, as if this time I've really disrespected him. "I mean you make it sound like a game or something. It's for real. You know what I mean? To pimp a bitch is a craft. You couldn't pimp a bitch if I put you in a room with a hundred hos. It's a craft. Some have it, and some don't."

Perhaps his attitude to women hasn't changed so radically. What about homosexuality? "I don't have a problem with gay people. I got some gay homies." He looks round the room and laughs. "Yeah, for real. People who were gay used to get beat up. It was cool to beat up on gay people back then. But in the 90s and 2000s, gay is a way of life. Just regular people with jobs. Now they are accepted, not classified. They just went through the same things we went through as black."

He recently spoke out in support of gay marriage in America. Does he think that Frank Ocean coming out is a sign of progress in the rap world? "Frank Ocean ain't no rapper. He's a singer. It's acceptable in the singing world, but in the rap world I don't know if it will ever be acceptable because rap is so masculine. It's like a football team. You can't be in a locker room full of motherfucking tough-ass dudes, then all of a sudden say, 'Hey, man, I like you.' You know, that's going to be tough."

Some people have been sceptical about the genesis of Snoop Lion. In the film Reincarnated, reggae legend Bunny Wailer welcomes Snoop to the fold, but he has recently said he feels betrayed; that Snoop's a fake who has let down the Rastafarian community. What does Snoop think he means? "I don't know, you would have to ask him." Does it upset him? "Either you going to roll with or you roll against. I don't roll against what I love. I love what I love. So even if he's shooting negative energy at me, I can't do nothing but match him with my love."

It's not hard to guess what upset many Rastafarians. The title Reincarnated refers to Snoop's statement that he is the reincarnation of Bob Marley. Does he really believe that? He looks me in the eyes and raps. "'Bob Marley reincarnated, pupils dilated, emancipated, concentrated, debated, rated many times, you defy how I made it? Huh?' It is me." I don't know it then, but he's quoting It Blows My Mind, a song he wrote in 2007.

Snoop's minder Killer tells us time is up. But Snoop isn't quite done. "I wanna shoot a shout-out to my homeboys in London: the princes, Harry and William. You know I raised them on this music of mine. They were groomed on me. How you think the Queen like that?" I think she'd hate it, I say. "Goddamn right," Snoops says, "but I'm a part of their revolt. They were at that age when my music spoke to them."

On my way out, I ask if he's still a big fan of Obama. His face breaks out into a huge smile. "Yeah, I love Obama. How could I not love him? This motherfucker got three states smoking weed legally now. And they talk about getting Texas, too. If we can get Texas, goddamn it, it's a wrap. That's what our president did for us."

Did he ever think there would be a black president in his lifetime? "I thought Jesse Jackson could win one time in the late 80s. 'You can win Jesse, you can win.' Then Jesse bullshitted, and fell back in and took the money. Then I had no hope. Ain't no nigga ever going to win, and if the nigga do win, they gonna kill him as soon as he get in office. But this president was different. He was sharp, he had the swagger of a real player but he had the conversation the other people related to, so he wasn't just talking to black people. He made everybody feel he was their guy, and now he's in office doing his thang, he's our guy." Once he starts his Obama love-in, there's no stopping him. "More niggas have been in that White House in the past four years than the entire amount of years that motherfucker was built. And I ain't just talking about sports teams, I'm talking about barbecues, bingo nights, all kinds of shit. Obama cleared out all the music when he got in there. He was like, hold on, clean that music system, get that bullshit outta here. Get some hip-hop, get some motherfuckin' old-time Motown. The refrigerator, he redid all that; get that bullshit out, get some ribs in here." He passes me the spliff. "Hit it one more time. He had some of that in there, too. In the Oval Office. You think he didn't?"

Would Snoop ever go into politics? "Probably," he says casually. "Probably as an old man. If I could make a difference."

But you'd have to cut down on the smoking, I say. "Sheeeeeit. Why? How d'you know politicians ain't smokin' like a motherfucker now?"

It would mean another radical change, but I wouldn't put it past him. Snoop President – the ultimate brand.

• The film Reincarnated is out now; the album is released on 22 April.