According to The Sun, the Masterchef star has proposed to his girlfriend Anne-Marie Sterpini, who is 21 years younger than him.
The couple have been together for two years.
The greengrocer-turned-presenter, 50, confirmed the news, telling the newspaper: “I’ve never been happier.”
Gregg separated from his third wife Heidi – a young teacher who had contacted him on Twitter to ask him a question about celery – in 2012 after 18 months.
He admitting cheating on his second wife, Denise – the mother of his two children – with other women.
Gregg’s first wife, Christine, left him after six weeks of marriage in 1991.
He took part in this year’s Strictly Come Dancing, but was the first celebrity to be voted out of the competition, alongside his professional partner Aliona Vilani.
Gregg told the Daily Star Sunday before he took part: “My girlfriend was happy for me to do it but she’s not sure how she’s going to feel about me spending so much time with another woman.
“She’d be happy if I was partnered with a man. One thing she’s already told me is that she can’t promise she won’t get jealous.”