The presenter and This Morning chef confirmed they had gone their separate ways in separate messages on Twitter, with both insisting the split is amicable.
“After more than 20 happy years together, Phil and I have decided to go our separate ways,” she wrote. “We will always share a great friendship and our lovely children.
“We would appreciate it if our privacy is respected at this time. Thankyou for your continued kindness and support.”
The former This Morning and Ready, Steady Cook host married the celebrity chef in 2000 following her split from Clive Jones in the same year.
Phil split from his ex Sarah Ann Lock in 1999.
The couple have a 17-year-old daughter, Winnie together. Fern also has twins Harry and Jack, and daughter Grace, with ex Clive.
Phil and Fern met on This Morning, when Fern hosted alongside Philip Schofield.
Speaking about the beginnings of their romance, Fern told the Telegraph in 2016: “The boys were four; Grace hadn’t even started toddling.
“I remember thinking at the time that nobody was going to take a 40-something woman with three kids.
“Then, one day at work, someone said, ‘Phil Vickery fancies you.’ And I went, ‘Remind me - which one is he?’
“Eventually, I kidnapped him, put him and his dirty washing - he was single at the time - in my car and drove him home. The next day, he baked me his irresistible gooseberry crumble.”
She added: “He is my life’s great love, a really amazing husband, partner, friend.”