He's paid his dues ... time after time ... and now Adam Lambert says he's been chosen to replace Freddie Mercury as the new lead singer of the legendary rock band Queen!!!! (Maybe not. See update below.)

Lambert KILLED IT with the band when he rocked out a rendition of "We Are The Champions" with the guys at the "American Idol" finale back in 2009 ... the first time he ever met the band.

30-year-old Lambert explained, "The intention is to pay tribute to Freddie and the band by singing some f*cking great songs. It’s to keep the music alive for the fans and give it an energy that Freddie would have been proud of.

So, we gotta ask ...