The 6ft 5in (1.96m) star, who has 52cm biceps and eats 10,000 calories a day to maintain his physique, has appeared on Gladiators since its return in 2024.
In January, he confirmed he had dropped his double-barrelled surname Christian-Johal in favour of Bigg, following his divorce and a recent diagnosis of attention deficit hyperactivity disorder (ADHD).
The post said: “To my Gladiator family. I want to tell you all that I won’t be coming back for season 4 of the TV show.
“Being a Gladiator has been one of the greatest honours of my life.
“Stepping into that arena, hearing the crowd, representing strength, resilience and being a role model… that’s something I’ll carry with me forever.
“What I do want to make clear is this wasn’t a decision I made to step away.
“I was faced with a choice that didn’t align with my values. And if you know me, you know this… I stand by my people and I stand by what I believe in.
“That’s what being a role model means to me. I’m proud of everything I gave to the show and grateful for every single person who supported me along the way.
“This isn’t the end. It’s just the beginning. Stay strong. Stand tall.”