The 47-year-old Cambridge graduate, who has been the show’s number queen since it first aired in 1982, marked her final appearance on Channel 4 yesterday afternoon.
Vorderman fought back the tears as she paid tribute to the show’s loyal fans.
She said: “I want to say what a complete privilege it has been to work on Countdown. It has been a privilege to meet tens and tens of thousands of you in the street and you all say how much you love Countdown.
“People who have been in hospitals with their parents when they have passed away and all they wanted to do in their last days at a particular time in the afternoon was watch Countdown. It means a lot to them. And to all the students who ribbed us over the years, I want to say thank you.
“I hope that you would agree with me that what we have always wanted Countdown to be — Richard [Whiteley] and I and Susie [Dent] and others who have worked on it — is always innocent and always kind.
“I just want to thank you for being our friends and my friend, and I shall miss everybody.”
She will be replaced by 22-year-old Rachel Riley, who fought off competition from more than 1,000 others to take over from Vorderman for the new series in January.
Yesterday’s show also marked the end of Des O’Connor’s time in the host’s chair — he is to be replaced by Sky Sports presenter Jeff Stelling.
O’Connor took over the show in January 2007, replacing Des Lynam, who stepped in following the death of much-loved Richard Whiteley.
Countdown was the first show to be broadcast on Channel 4 when the station was launched in November 1982.
Vorderman has taken part in the BBC’s Strictly Come Dancing and the family history show Who Do You Think You Are? as well as fronting the Pride of Britain Awards.
She also launched a range of Sudoku products and penned a number of detox diet books.
But it is her role on Countdown made her one of the highest-paid women on television.
Vorderman was the first woman to appear on Channel 4 providing a stark contrast to the traditional “glamorous assistant” role for female game show hosts.
The 47-year-old, who has an IQ of 154, was awarded the MBE for Services to Broadcasting in the New Year’s Honours List 2001.
Before joining Countdown, Vorderman sang in a group called Dawn Chorus and the Blue Tits, alongside radio DJ Liz Kershaw.