Eddie Howe's team were handed the initiative inside the first minute when Gabriele Angella brought down Callum Wilson and referee Lee Probert adjudged the Watford defender to have denied a goalscoring opportunity, producing a red card.
Bournemouth could not make their numerical advantage could until 10 minutes before half-time when Wilson went to ground once more - in the box on this occasion - under a challenge from Craig Cathcart.
Yann Kermorgant converted from 12 yards and the hosts doubled their advantage after 57 minutes.
Kermorgant turned provider as he picked out Matt Ritchie to drill a low strike beyond Watford goalkeeper Heurelho Gomes for his eighth goal of the season.
Gomes stopped Marc Pugh from adding gloss to the scoreline two minutes from time as Bournemouth returned to winning ways following defeat to Leeds United last time out in the Championship.
They lie three points ahead of Derby County, who travel to Cardiff City on Saturday, while Watford occupy the final play-off spot.
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