Betfair marked his odds of winning at 9/2 with Eastenders star Rose Ayling-Ellis just behind him with odds of 11/2,
At the other end of the scale, Judi Love has odds of 25/1 to win as does actress Nina Wadia.
Betfair spokesperson Sam Rosbottom said: “On the eve of the UK’s most glamorous show starting, Tom Fletcher is the 4/1 favourite to waltz his way to the Glitterball trophy, while Rose Ayling-Ellis (11/2) and Rhys Stephenson (6/1) are close on his heels.
“Adam Peaty is 10/1 to follow up Olympic Gold with the Stricly crown, while Robert Webb is 8/1 and AJ Odudu 10/1.”
Strictly Come Dancing is available to watch on BBC iPlayer now.