Herdman started acting when he was about seven years old and one day Martin found him an agent. Herdman also had a child with his partner, Jessica – the couple had a son, Morgan.
Herdman began his MMA career on 23 April 2016 in Romford with a decision win over Janusz Walachowski. He said, "I chose MMA because I love the sport. It's raw, exciting and unpredictable. I find it more interesting than boxing although I appreciate the beauty and art in boxing. It also made sense to move onto MMA because of my jujitsu training. I would like a few amateur fights first to get me started and where it goes from there, who knows?"