The 30-year-old decided to pop the question to his other half during a photoshoot at the home of English football.
"It was the last place Gemma wanted to be," Barker told The Sun. "But I wouldn't take no for an answer and forced her to come along.
"She didn't have a clue what I was intending to do. I'd arranged to have a message put on the big scoreboard, 'Will you marry me Gemma?'. Lucky for me, she said 'Yes'!"
Barker is due to fight at Wembley Arena next month.