The X-Factor judge, who became a mother for the first time earlier this year, won the accolade for the second time in three years following a readers' poll in UK newspaper the Metro.
The 39-year-old singer, who has also branched out into fashion design, wrote an open letter thanking fans for helping to make her year a great one. And she said she's got more projects in the pipeline for 2011.
She wrote, 'This year has been insane. I've done all the things I really wanted to do.
'I'll be doing stuff with [fashion label] Project D, a few new chapters for the paperback of the book [her 2010 autobiography] and X-Factor I hope.
'That's everyone's biggest question. What's happening in the US and here? Is it still on? Are the dates changing? I have just as many questions as you guys.'