And boss Slavisa Jokanovic was naturally pleased with the performance - one he says was 'very close to perfect.'
"We can be happy," Jokanovic told Sky Sports after the rather convincing win. "After a bad November we have started December better. It was very close to a perfect performance after some bad results.
"We played a fantastic game. I must to be happy, I expect my players and supporters go home happy.
"In the last few games we did not have control and offered up to many presents. Today we were in control. But in front of us is a big space to improve."
Deeney, meanwhile, looked distraught when he wasn't handed named man of the match after the game - the decision was made before he scored a third.
But nothing could take the match ball away from the 26-year-old, who absolutely shone as Watford put Fulham to the sword. Here's how Watford fans saw Deeney's performance on Twitter...
Switched off a bit at 4-0 but who cares? Deeney hat-trick, Gibbs return tops off the night. Abdi sensational. Top win. You. Orns. #watfordfc— Adam Drury (@Adam_Drury1) December 5, 2014