The first half ended in a goalless draw but all it took was 12 minutes for the Gunners to rack up a three goal lead.
Alexis Sanchez opened the scoring on 62 minutes after being setup by Mesut Ozil.
The World Cup winner provided his second assist just six minutes later setting up Olivier Giroud.
Aaron Ramsey wrapped up the win on 74 minutes to take home all three points.
Arsenal have never lost against Watford in the Premier League with Arsene Wenger in charge.
The Gunners have now lost just once in their last eight league games and go into the game in second place just two points behind leaders Manchester City.
Watford v Arsenal
Stadium: Vicarage Road
Kick-Off: 17:30 GMT
Arsenal Confirmed starting XI: Cech, Bellerin, Mertesacker, Koscielny, Monreal, Coquelin, Cazorla, Ramsey, Ozil, Sanchez, Walcott.
Watford Confirmed starting XI: Gomes; Nyom, Cathcart, Prodl, Ake, Anya, Capoue, Watson, Abdi, Deeney, Ighalo.
Goals: 62′ Sanchez, 68′ Giroud, 74′ Ramsey