The Hornets are the favourites to land the 24-year-old on a loan deal in January, according to The Mirror.
The 24-year-old moved to the Bianconeri from Sassuolo for a fee of €18 million (£12.9m) in the summer, but has struggled for game time in Turin.
Max Allegri has preferred to partner Paulo Dybala and Mario Mandzukic in attack this season, with Zaza only receiving three Serie A starts so far this term.
The report also suggests Zaza’s move could be made permanent if all parties agreed next summer for a fee of £3.5 million, which seems unlikely given how much Juventus paid for him only six months ago.
Watford have had an impressive attacking partnership between Troy Deeney and Odion Ighalo this term, with the Vicarage Road strike duo both getting on the scoresheet at the weekend and firing the Hornets into a top-half position.