The Hornets were made to work hard for their eighth point of the season, in what was a fifth draw between these two sides in the last six meetings.
There was an early chance for Odion Ighalo to edge the hosts ahead when latching on to a flick-on inside the box, which he flashed wide of the far post.
Both teams looked to get forward but there were no real chances until Junior Stanislas whipped in a fine cross for Callum Wilson to head low past Heurelho Gomes on the half-hour mark, making it seven goals from 12 shots for the Englishman.
Artur Boruc was needed to twice deny Nordin Amrabat soon after, but Wilson was also causing real damage up the other end as the Cherries looked for their first three-point haul on their travels this season.
Watford did level up shortly after the restart when, just minutes after coming close through an acrobatic volley, Troy Deeney was able to blast home from close range for the hosts.
Jack Wilshere almost put Bournemouth straight back into the lead 52 minutes in when coming close with a curled shot, and that miss so nearly proved costly as only a fine Boruc stop denied Deeney a second.
An inspired substitution by Eddie Howe helped Bournemouth restore their advantage on the hour, as the fit-again Joshua King came off the bench to add a second for his side with a deflected long-range drive.
Watford again showed good character to respond, however, with Isaac Success meeting a deep cross into the box to add the fourth goal of the match in what was proving to be a thrilling affair.
Wilshere missed an even better chance 15 minutes from time when hitting the post from close range, while Stanislas also picked out the crossbar from a free kick, but Howe's men just could not find a way through for a third time.