The first-half effort was enough in a game that put the Vicarage Road outfit into the automatic promotion spots, albeit possibly only temporarily.
After finding the net twice in midweek, Andre Gray nearly added his third of the week after just four minutes, when he connected to a cross by Kiko Femenia, but his effort was collected by goalkeeper Brice Samba.
The home side continued to have the majority of the early play, and they took the lead after 17 minutes.
Ismaila Sarr beat Bong on the right flank and fired in low for Samba to parry. Masina picked up the ball in the area and aimed his effort past the goalkeeper.
Watford continued to look the more dominant team, and Pedro could not keep his effort after 27 minutes down, from a corner by Philip Zinckernagel.
Forest offered little attacking threat, with a wayward effort from Filip Krovinovic just after the half-hour mark their first worthy attempt.
Watford almost doubled their advantage six minutes after the restart, when Pedro picked up a through ball from Zinckernagel, but his tame effort was collected by Samba.
The home side came close again after 56 minutes, when Gray just failed to connect to a low drive across the face of goal by Femenia.
With one goal still separating the sides, the visitors were still very much in the contest, and Bong headed wide after 72 minutes from an Anthony Knockaert cross.
Zinckernagel could have settled the contest with 77 minutes gone but his effort was directed over the crossbar.
Former Watford midfielder James Garner scuffed an effort wide with three minutes remaining, while a shot from Taylor that found the target was ruled offside.
The home side were able to close out the three minutes of injury time to put them at least temporarily in second place in the Championship.