The Hornets are the 98th and final team to earn three points from a fixture in Europe's top five leagues. They were also the last outfit to win in the four professional tiers of English football.
Quique Sanchez Flores' side moved off the bottom of the Premier League at the expense of Norwich thanks to Gerard Deulofeu's early individual effort and Andre Gray's deflected backheel. The goals came from Watford's only shots on target.
The Canaries failed to take advantage of numerous attacks spearheaded by Onel Hernandez in the opening half and then couldn't seize on their numerical edge when Christian Kabasele received a second yellow card in the 65th minute.
Norwich have taken one point from a possible 21 since their famous 2-1 defeat of Manchester City in mid-September.