Cowell is the first judge announced for the show's 11th series and the rest of the panel will be revealed in the coming months.
"I'm absolutely thrilled to be returning to The X Factor UK. It's been three years since I last judged the competition and I'm excited to find a global superstar again," said Cowell.
"The UK X Factor has set the benchmark in finding worldwide superstars over the years - including One Direction, Leona Lewis, Cher Lloyd, Olly Murs, JLS and Little Mix."
Cowell departed the UK series in 2011 to launch a US version of the talent show for the Fox network. However, the US series got off to a bad start with first pick judge Cheryl Cole leaving after only a few days of filming and original host Steve Jones being mocked by American TV critics.
The record label boss predicted that the show would get 20 million viewers, but it never came close to that figure and it was also easily beaten by rival talent shows American Idol and The Voice. It also, most importantly, never found a breakout star.
Cowell hinted at the end of last year that he might return to the UK show as the American version is expected to be stripped back in 2014.
The show's creator was coy about who would be joining him on the panel, commenting: "Despite all the rumours, ITV and the producers have not decided on the rest of the judging panel quite yet. You'll just have to wait and see…."
Louis Walsh is expected to return for his 11th year on the show, despite claiming last year would be his last, while rumours of a Cheryl Cole comeback are bound to resurface now that Cowell is back in the mix.
Other potential judges for 2014 include Rita Ora, Tinie Tempah and Nicole Scherzinger.
Auditions for X Factor series 11 start in June.
The show remains one of ITV's biggest ratings hits despite a recent decline in viewers. An audience of over 10 million tuned in to watch prison officer Sam Bailey win last year's final.
ITV's director of television Peter Fincham said that it was "fantastic" news to have Cowell back on the UK show, while producers Fremantle's CEO Sara Geater claimed that his return signalled "a great series" was ahead.
Cowell's return coincides with the launch of Harry Hill's X Factor musical I Can't Sing, which is launching in the West End in March.
The 54-year-old mogul is also expecting his first child later this month with Lauren Silverman.