July 24, 2019. Raw footage: Bindi Irwin is seen celebrating her 21st birthday at Australia Zoo in Beerwah, Queensland. (AAP VIDEO/Darren England)

Bindi Irwin is engaged to boyfriend Chandler Powell after he proposed on her 21st birthday at her favourite location in Australia Zoo.

Bindi posted the happy news on Instagram, sharing a photo of her stunning engagement ring.

“July 24th 2019. On my birthday I said ‘yes’ and ‘forever’ to the love of my life,” she captioned a photo of the couple.

“Chandler, close to 6 years ago I fell in love with you and every day since has been a whirlwind of adventure and true happiness.

“I’m so looking forwarding to spending our forever together as your wife. Here’s to a lifetime of friendship, purpose and unconditional love. — Now let’s get married already!”

The couple were flooded with wellwishers, with Bindi’s brother Robert commenting a series of love heart emojis.

Chandler, 22, also shared a post celebrating their engagement, revealing he had proposed to Bindi at Australia Zoo.

“She said YES! Almost 6 years ago we met at Australia Zoo. I immediately fell head over heels for her kind and thoughtful heart that radiates so much light.

“Proposing in her very favourite place in the zoo, surrounded by animals, seemed like the perfect way to embark on this incredible new chapter in our lives. Bee, I love you more than anything in this world and I always will. Happy Birthday.”

Proud mum Terri also shared her well wishes for the couple on Twitter, revealing she was “so very happy, and I know Steve would be too”.

Best day ever! Chandler asked and beautiful @BindiIrwin said yes. I am so very happy, and I know Steve would be too. Congratulations!! pic.twitter.com/sN5sFnxZhI — Terri Irwin (@TerriIrwin) July 24, 2019

I am beyond happy for you two. You are true soulmates and have always been so completely perfect for each other. Love you both and congratulations 💍 pic.twitter.com/zrjXIFTegn — Robert Irwin (@RobertIrwin) July 24, 2019

Earlier on Wednesday Chandler had been by Bindi’s side as she celebrated her 21st birthday at Australia Zoo.

The couple looked smitten as they posed for photos together, with Bindi blowing out the candles on a bumblebee cake.

Bindi and her younger brother Bob are the children of animal conservationist and TV personality Steve Irwin, who died from a stingray barb in 2006 when Bindi was just eight years old.

She began appearing on TV from the age of two including on her father’s The Crocodile Hunter series which also featured her mother, Terri.

Bindi received a standing ovation after delivering a eulogy for her father at Australia Zoo at a memorial broadcast worldwide to a TV audience of more than 300 million viewers.

Bindi’s star was on the rise thereafter, appearing on magazine covers, the Ellen DeGeneres Show, and the Late Show with David Letterman.

She launched her own video, Bindi Kid Fitness, and became a tourism ambassador for Australia, and won a Logie award in 2009 for most popular new female talent.

A passionate conservationist like her parents, Bindi was awarded Young Conservationist of the Year in 2014 by the Australian Geographic Society.

This year, she was a guest judge on the Australian Dancing With The Stars.

Bindi and Chandler, a professional wakeboarder from the US, met in 2013 when she gave the American and his family a tour of Australia Zoo.

Chandler now works alongside the Irwins at Australia Zoo, with Bindi describing him as “my always” in an interview with Stellar published on the weekend.

“He’s so kind and solid and always there for me. I think it’s really rare to find that so early in life,” Bindi said.

“My mum and dad always described their marriage as feeling like a special pair of old shoes — knowing you can always depend on someone. I know it’s the same with Chandler. At the end of the day, when I’m exhausted, he will be there even if I don’t have make-up on or my hair is crazy and I’ve been wearing the same shirt for three days.”

Despite their young age the couple have faced engagement rumours for years, with speculation amping up in the last 12 months.

“There’s always a few engagement rumours swelling, but I promise you, I can clear the air, we’re not engaged yet guys,” Bindi told E! News in October last year.

“But I swear I will let you know when it happens, really.”