It follows current presenter Nick Hewer announcing he was stepping down from the show last year.
Nick, who first found TV fame as an adviser to Lord Sugar on The Apprentice, has been hosting Countdown since 2012 after taking over from Jeff Stelling.
News of Anne Robinson stepping into the role was first announced on Channel 4's Steph's Packed Lunch today (15 February).
TV and presenter Anne is best known for fronting The Weakest Link for more than 10 years between 2000 and 2012 as well as shows such as Watchdog.
Anne Robinson said today: “I am beyond thrilled to be joining Countdown. The show is almost as old as I am and just as historic. I am particularly excited to be working alongside the Show’s two other formidable women.
"Worryingly, Susie and Rachel are not only very smart but younger, prettier and thinner than me. Sadly, there’s no time for another face lift so I'll have make do with this old one.
“Three Clever Girls Do Countdown! Don’t you love the sound of that?
“I am a crossword nut so the Countdown’s conundrums I can make sense of. But the adding up and taking away - I can't go much further than working out the fee once my agent takes his cut.”
Nick had announced his exit on Twitter in December.
He wrote: "Delighted to be back in the Countdown studio after another enforced lockdown, BUT this latest lockdown has given me an opportunity to consider my future life and I’ve decided it’s a good time to step down at the end of my contract in the New Year.
"As someone in his 77th year, who will be in his 10th year hosting the great British institution that is Countdown, I think it’s time to smell the flowers and get a dog.
"But let me now take the opportunity to say that it’s been a privilege and a pleasure to take the helm of Countdown, first broadcast back in 1982 and still a Guinness recordholder...
"Although I’ll be on your screens well into 2021, let me thank the broadcasters Channel 4, the truly dedicated and unwaveringly professional studio crew and production staff at ITV Studios who make the programmes, all 250 or so a year, my wonderfully talented co-hosts Susie Dent and Rachel Riley but above all, the quirky genius of producer Damian Eadie, who never ceases to amuse and who always demands the best of us.
"And a sincere thanks to our loyal viewers and of course the legions of contestants who battle their brains out for the chance of carrying off the Richard Whiteley Trophy or a priceless teapot. And so, to whoever takes my seat, I wish you every success and hope that you have as much fun and reward as I’ve enjoyed."
Countdown airs weekdays on Channel 4. You can watch episodes online via the All 4 player here.