The former Big Brother contestant-turned-TV presenter joins Andy Murray's mum Judy and The Saturdays star Frankie Sandford as the first celebrity dancers announced.
Alison had been widely tipped as a rumoured contestant.
"I am absolutely overjoyed to be joining the Strictly team," said Alison, 39. "I am ready to immerse myself in glitter and hard work, with a dash of fun along the way!"
Alison shot to fame on the third series of Big Brother back in 2002, before landing a role as showbiz reporter for This Morning, interviewing the stars.
The new series of Strictly kicks off on BBC One later this year.
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