"I've loved every minute."
The presenter brought the series to an end with a low key finale in which he was presented with a bouquet of flowers as he said farewell to the audience.
The series has been axed by ITV, although for many years its place in the schedule had been reduced to occasional screenings - largely with well-known faces teaming up to answer questions for charity.
Viewers saw Millionaire come to an end last nightwith a celebrity special which included appearances by Sir Chris Hoy, who teamed up with comic Kevin Bridges, and James Nesbitt, paired with Dom Joly.
But any hope of finishing with a big cash win were dashed by the final duo to face Tarrant, Countdown star Rachel Riley and Hairy Biker Dave Myers. The duo rounded off the show by winning just £1000 for charity, losing out on £19,000 with their final wrong answer.
In the final seconds of the show, Tarrant gave a simple farewell after being presented with a bunch of flowers by the production team,
Thanking viewers, he said: "Bless you, it's been a fantastic 15 years. I've loved every minute. There have been lots of magical moments. All that remains is for me to thank all of our splendid guests who have braved the hotseat tonight - and over 15 years. And all the millions of you at home for watching.
"From all of us on Who Wants To Be A Millionaire - good night and goodbye," he added before the studio was filled with glittering ticker tape.
Since launching in 1998, the format has launched around the globe, becoming one of the most successful programmes in the world, launching spin-off games and becoming the inspiration for Danny Boyle's hit movie Slumdog Millionaire.
A special programme looking back over the programme's outstanding moments will be screened next Tuesday on ITV.