Emile Smith Rowe's second-half goal was enough to give us victory in Mikel Arteta's 100th game in charge.
We had to work hard for all three points though, after a missed penalty in the first half and disallowed goals either side of the break.
After a minute's silence ahead of Remembrance Sunday next week, we made a promising start at the Emirates.
Ainsley Maitland-Niles was the only change to the side that beat Leicester last weekend, replacing the injured Thomas Partey in midfield. And his clever pass to Alexandre Lacazette inside the box led to us having the ball in the net after just seven minutes, but it was ruled out by VAR.
Lacazette's lob found Pierre-Emerick Aubameyang, from him the ball bobbled to Bukayo Saka, but replays clearly showed his was offside as he stroked home.
The game became scrappy for a while after that, with neither side taking control.
There were more yellow cards than shots in the opening half hour - two apiece - and it was a foul in the area that gave us a golden opportunity to take the lead.
Lacazette was taken out in the box by Danny Rose, only for Aubameyang to see his spot kick saved by Ben Foster, who also gobbled up the rebound.
Late in the half Foster also denied Gabriel well with his legs, when the big defender got his head to an inswinging Saka corner.
The second half started in similar fashion, with both sides picking up more bookings before we eventually made the breakthrough.
Ben White took control, surged forward towards the area before the ball fell to Smith Rowe just outside the box. His low shot found the corner, with Watford players appealing for a foul on Moussa Sissoko.
The goal was given though, and Smith Rowe had scored for the third Premier League game running.
We had another goal disallowed, when Aubameyang sliding in on the line to get the final touch to a Martin Odegaard shot, but the flag was quickly raised. The frustration was that it appeared as though Odegaard's shot may have gone in without Aubameyang's touch.
Watford were not laying down and began to put us under more pressure in the closing stages.
There was a real scare when Josh King rounded Ramsdale outside the area, found himself with an open goal but shot into the side netting.
Juraj Kucka was sent off late on for the visitors, for a second bookable offence, and then Sambi Lokonga could have sealed it with a piledriver in injury time, but Foster batted it away.
1-0 to the Arsenal it was though, enough to lift us to fifth place before in the international hiatus.
WHAT IT MEANS
* This was Mikel Arteta's 100th game as Arsenal manager, the full record is: P100, W56 D18 L26 F163 A97.
* He is the 15th Arsenal manager to reach the landmark.
* His first game in charge was away to Bournemouth on December 26, 2019 (drew 1-1).
* He has the joint highest win percentage of any Arsenal manager for their first 100 games (with George Graham).
* Emile Smith Rowe's goal was the 100th we have scored in the Premier League under Arteta.
The international players will join up with their countries before domestic football resumes in two weeks' time.
Our next match is away to Liverpool in the Premier League, on Saturday November 20 at 5.30pm (UK).
Copyright 2023 The Arsenal Football Club Limited. Permission to use quotations from this article is granted subject to appropriate credit being given to www.arsenal.com as the source.