Newcastle hit the Hornets early with a goal thanks to Fabricio Coloccini, the Argentinian defender headed home a Danny Guthrie free-kick, now giving him a total of two goals for the season.
Watford pressured the Magpies after their first goal forcing Steve Harper into action to keep Newcastle in front.
Newcastle made hard work in doubling their lead but managed to get their two goal cushion courtesy of striker Carroll. The young Gateshead born forward headed comfortably past Scott Loach from a Danny Guthrie corner.
Watford grabbed a late consolation goal in stoppage time with Hoskins finishing from close range. But with only a few minutes remaining, United held on to get the three points.