Singer Styles, who made his acting debut in Dunkirk last year and received strong reviews, has had a flurry of bets placed on him in recent days.
Now, Coral have cut his odds down to 8/1, closing in on the frontrunners.
Tom Hardy remains in the lead on 2/1, after – coincidentally enough – also starring with Styles in Dunkirk last year.
James Norton is also prominent on the list – he’s in second place on 4/1, as speculation around his James Bond casting continues hand-in-hand with his work in McMafia.
Coral’s Harry Aitkenhead said: “If the directors do opt for a younger James Bond to step into Daniel Craig’s shoes then Harry Styles could be a contender.
“Punters clearly think his cameo in Dunkirk could be the start to bigger things for the One Direction star.”
Overall he is joint-fourth in Coral’s rankings, with Jack Huston also a strong contender on 5/1.
Styles joins Idris Elba and Aidan Turner with 8/1 chances.
Excitement around Styles’ potential casting intensified when writer Lee Smith, who edited Spectre, said: “Harry could do it. If they wanted a younger Bond then why not? He has got it.”
Speaking to the Daily Star, he went on: “Harry is really good and he can go all the way. He is an exceptional talent and a complete natural on camera.
“You would have thought you were dealing with a guy with many years of experience. You would never know that [Dunkirk] was his first film. I didn’t know who Harry was.”