Robert Irwin has reportedly caused some trouble with his mum after enjoying a night out in Vegas with a mystery woman.

The 21-year-old — who is set to appear on the US version of Dancing With The Stars — travelled with his mum, Terri, and sister, Bindi, to Las Vegas for the annual Steve Irwin Gala on May 10.

But what was meant to be a wholesome trip descended into chaos when Robert left his family to grab dinner with a blonde woman.

Photos emerged of the pair walking closely together down the Vegas strip and beaming with happiness as they sat next to each other in the corner of a small ramen restaurant.

A source close to the family told Daily Mail Australia that Robert’s antics have “deeply disappointed” Terri.

“Terri doesn’t care who the girl is. She just thinks the whole thing looks really bad, especially with Robert about to appear on the US version of Dancing with the Stars,” the insider told the media outlet.

“While the cat’s away, the mice will play.

“Robert doesn’t usually get much downtime, so he let his hair down but Terri was expecting him to keep things low-key, not hit the strip with a blonde on his arm.”

The wildlife warrior was left to his own devices when his sister and mum were forced to pull out of the Gala after Bindi suffered a ruptured appendix and had to undergo emergency surgery.

The insider told Daily Mail that Terri is now trying to calm speculation that his late-night antics will impact his upcoming appearance on DWTS.

“They’re in full damage control. The line from the Irwins is ‘there’s nothing to see here’. But behind closed doors, Terri is fuming,” they said.