The identities of the final three celebrity contestants were unveiled on BBC One's One Show on Friday evening (29 August), meaning the full lineup has now been revealed.
"I absolutely love the show and I love dancing! I cannot wait to get engrossed and live in a Strictly bubble!" said Gregg.
Tim added: I'm delighted to be joining Strictly Come Dancing. My wife and I are big fans of the show and this year we'll be celebrating our 30th wedding anniversary. She loves dancing but it's never really been my speciality. I would love to pick up even just a few moves so that come our anniversary, I can take her out and show her a good time!"
Meanwhile, Jennifer said: ""As a child I wrote to Blue Peter asking could I dance with Pan's People. Now at last I get a chance to earn my badge - excited doesn't cover it!!"
MasterChef judge Gregg, Bargain Hunt's Tim and Mrs Brown's Boys actress Jennifer join a glittering group that includes former Xtra Factor presenter Caroline Flack, The Saturdays' Frankie Bridge and ex-TOWIE star Mark Wright.
Also competing are popstar Pixie Lott, EastEnders actor Jake Brown, BBC Radio 1 DJ Scott Mills, Blue singer Simon Webbe and This Morning reporter Alison Hammond.
Naturalist Steve Backshall, Casualty star Sunetra Sarker, Andy Murray's mum Judy and ex-rugby player Thom Evans.
This year's Strictly will be co-hosted by Tess Daly and Claudia Winkleman following Sir Bruce Forsyth's decision to step down from the main shows.
Strictly launches Sunday, 7 September at 8pm on BBC One.