North End fell behind in the 13th minute when Andreas Weimann, on loan from Aston Villa, got on the end of a cross from Danny Graham to fire past Iain Turner.
The home side levelled in the 28th minute when Barry Nicholson's 30-yard effort eluded Hornets goalkeeper Scott Loach. They moved in front 11 minutes into the second half when Iain Hume notched his 12th goal of the season with a 25-yard free-kick.
Brown`s side wrapped up the points with two minutes left when Jamie Proctor claimed his first professional goal from close range after being set up by Keith Treacy.
The win moved them above Sheffield United and Scunthorpe, something which pleased Brown.
He said: "It is a proud feeling to not finish bottom. You always have to play with a purpose and ours was to get above the two teams immediately above us. It looked like we had been promoted which is astounding - the fans are a million percent behind what we are trying to achieve. They want to see passion from our players."
Source: PA
Source: PA