Javier Hernandez continued his inspired run of form, scoring his third goal in four Premier League games, while Marko Arnautovic marked his return to the starting eleven with a goal.
New signing Patrice Evra was sat on the bench for the Hammers with Arnautovic, Michail Antonio and Pablo Zabaleta returning, while rather unsurprisingly Watford opted for the same starting eleven that thumped Chelsea on Monday.
The Hammers then replied themselves through Arnautovic's dazzling feet. He made his way into the penalty area past three Watford players and when he was eventually brought to a halt, the ball fell kindly to Joao Mario but Orestis Karnezis denied him of his first goal in a claret and blue shirt.
Arnautovic then had a golden chance to open the scoring but squandered it from point blank range. He latched onto a header down into the six yard box but put his shot straight at Karnezis. Chicharito saved his blushed seconds later though.
After the restart, Deulofeu hit a dipping free-kick but Adrian was able to palm it away. West Ham were beginning to assert themselves as the dominant force in the game and Karnezis - while not seriously tested - was becoming busier.
GOAL! Arnautovic has doubled the lead for the Hammers!#WHUWAT— 90min (@90min_Football) February 10, 2018
The win moves West Ham up to 12th place, level on points (30) with Watford in 11th.
| #watfordfc XI v @WestHamUtd | Karnezis (GK); Mariappa, Prödl, Holebas; Janmaat, Doucouré, Capoue, Zeegelaar; Deulofeu, Deeney (C), Richarlison.— Watford FC (@WatfordFC) February 10, 2018
Subs | Bachmann (GK), Mukena, Ndong, Pereyra, Lukebakio, Carrillo, Gray. pic.twitter.com/cr8hxk692d