The Spice Girls star was first linked to the comedian last week after they were snapped holding hands on a tour of Hampton Court Palace.
Insiders later claimed that the couple are "serious" and bookmakers have already offered odds on them marrying in 2013.
Halliwell has now confirmed her relationship with Brand, but played down reports that they are ready to commit to each other by describing herself as "choosy" with men.
"It's been a whirlwind," Metro quotes her as saying. "All I want is to be in a loving relationship.
"Is he my ideal man? I'm choosy. I want someone who's trustworthy, sweet and kind."
Halliwell's comments follow stories at the weekend that she is finding the ex-husband of Katy Perry "way too intense".
Photo gallery - Geri Halliwell and her exes:
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