Arnold Schwarzenegger's son Joseph Baena is set to compete on 'Dancing With The Stars'.

Arnold Schwarzenegger's son Joseph Baena for Dancing With The Stars

Arnold Schwarzenegger's son Joseph Baena for Dancing With The Stars

Baena, 24, who was revealed as the secret love child of Schwarzenegger and his housekeeper Mildred Baena in 2011, has been photographed by TMZ, making his way to rehearsals for the show in Los Angeles.

He will join other stars including Charli D’Amelio and her mother Heidi on the upcoming 31st season.

Meanwhile, Joseph - an actor who also works as a real estate agent - previously opened up about the day the world discovered his father was Schwarzenegger.

He said: "I remember the day very vividly. I was in the eighth grade. Fifth or sixth period. And I get called out of class to leave. And my mom’s there, and she’s like, ‘We gotta go—everyone is finding out about you and who your father is.’ I’m 13. Your body’s transforming; your mind is transforming. And now my life transformed before my eyes."

And Joseph admitted it was tough as he didn't know who to trust.

He said: "[My mom] was really the only person I had, and I was really the only person that she had. No one knew, and everyone wanted the details. We had each other’s backs.”

However, he and Arnold soon bonded over fitness as the actor gave him a copy of 'The Encyclopedia of Modern Bodybuilding' (which he co-authored) and later they started training together.

He said: "Even though I could call him anytime, I was too proud. I went straight to the book. I wanted to figure it out myself.

"I was so nervous. I was being observant, trying to see what he was doing and the way he was acting.

"I was able to acquire a bodybuilding mentality—that I could shape my body however I want.

"One of the big things I learned from Dad was not to have the ten-rep mentality. It's pushing yourself to the limits and going that extra mile, getting those extra reps and half reps till you’re basically dying."