Growing up fast! Robert Irwin, 20, flexes his biceps while spending family time with niece Grace Warrior, three

Robert Irwin has sent his fans into a frenzy by sharing a stunning photo of himself showing off his toned biceps while spending time with his niece.

The 20-year-old famed conservationist posted the adorable photo to Instagram on Friday, which shows him with his sister Bindi Irwin’s daughter Grace Warrior, three.

He beamed from ear to ear in the adorable photo, as he showed off his toned, bulging biceps and gently held his growing niece.

Robert couldn’t get the smile off his face as he brazenly acted for the camera, showing just how strong he is by effortlessly holding the young man down.

The reality star captioned the photo with the touching words: ‘An uncle for me!’

Many of Robert’s famous family members and friends were quick to respond in the comments, raving about the amazing photo.

“Thank you for being the best uncle and brother. We love you!” wrote Grace’s mother Bindi, and family matriarch Terri Irwin added, “Grace loves you so much!”

Meanwhile, The Wiggles star Lucia Field added: ‘OMG she hasn’t grown up this much! watttttt!!!’

Robert Irwin has sent his fans into a frenzy by sharing a stunning photo of himself showing off his bulging biceps while spending time with his niece Grace. He is smiling in the adorable photo as he shows off his toned and bulging biceps. Both are pictured

Bindi Irwin and her American wakeboarder husband Chandler Powell got married on March 25, 2020, and welcomed their daughter Grace Warrior exactly one year later, on their first wedding anniversary.

Robert and Bindi are the children of Steve ‘The Crocodile Hunter’ Irwin, who died on September 4, 2006 at the age of 44 off the coast of Queensland after a stingray stung him in the chest while filming a nature documentary.

Bindi was six years old when he tragically passed away, while Robert was three months away from his third birthday.

Robert couldn't get the smile off his face as he brazenly acted for the camera next to young Grace

Robert couldn’t get the smile off his face as he brazenly acted for the camera next to young Grace

However, his legacy lives on in his family, who have continued his mission of conservation and advocacy. There are rumors that Grace will follow in her family’s footsteps as she grows older.

It was Steve’s father, Bob, 85, who built the iconic Queensland zoo from scratch in 1970 and passed it on to his late son and wife Terri in 1992.

During his lifetime, Steve was committed to conservation with his own successful TV show, The Crocodile Hunter.

His family continued his legacy with their own blockbuster wildlife reality series, Crikey! It’s the Irwins, which debuted in 2018 and continues to air on the Animal Planet network.

Bindi Irwin and her American wakeboarder husband Chandler Powell got married on March 25, 2020 and welcomed their daughter Grace Warrior exactly one year later, on their first wedding anniversary. All pictured

Bindi Irwin and her American wakeboarder husband Chandler Powell got married on March 25, 2020 and welcomed their daughter Grace Warrior exactly one year later, on their first wedding anniversary. All pictured