The singers took time out from mentoring this year's finalists to celebrate at a lavish ceremony at London's Victoria and Albert Museum.
The former N-Dubz star was presented with the Ultimate TV Personality award, while ex-Pussycat Doll Nicole was named Ultimate Fun Fearless Female. As she took to the stage to accept her award, Tulisa said: "For the first time in many nights I'm actually sober! Giving myself applause for that!"
The X Factor judge thanked Cosmopolitan for putting her on the cover of the magazine and apologised for dying her blonde hair back to brunette just before it was published.
Arriving at the awards Nicole Scherzinger described her white backless dress as "like a mullet - it's like business at the front and party at the back". She was presented with her award by her X Factor finalists and said: "It made it so much better to have my little pumpkins up there giving it to me."
Cheryl Cole, who was replaced by Tulisa as a judge on the UK X Factor, and by Nicole on the US X Factor judging panel, won Ultimate Pop Star.
Accepting her Style Icon award, Kelly Osbourne said she felt her style had much improved over the years. She added: "Thank you so much Cosmo, when you put me on the cover of your magazine it gave me so much self esteem."
Fresh Meat star Zawe Ashton was presented with the Best Newcomer gong by her co-star Jack Whitehall. She joked: "Thanks Jack, I did want Nicole Scherzinger, but thank you."
One Direction's Harry Styles said in a video message: "We cannot believe we've been voted Ultimate Men of the Year because most people still say that we're boys."
The Cosmopolitan Ultimate Women of the Year Awards 2012 with VO5 were hosted by Radio 1 DJ Fearne Cotton.