The home side had looked on course for a fourth successive home win when Carl Dickinson scored a stunning 25-yard effort and Swansea loanee Craig Beattie reacted first to head home after Mark Yeates' effort had rebounded off the crossbar.
But City halved the deficit before the interval when Marvin Elliott headed in Ryan McGivern's cross, and equalised two minutes later when a poor touch from Watford keeper Scott Loach allowed Adrian Mariappa's routine back pass to roll into the net.
McInnes said: "We are happy to come away with a point because it is clear that we weren't at our best. We didn't have that sparkle we've shown in recent weeks, but we had the determination was there to make the situation better to make things happen.
"We had to stand up to the different style of football that Watford play. They get the ball forward and you can see why they have got such a good home record. They get after you and put you under pressure.
"Sometimes you have to accept that when you are not at your best then you just take the point. It keeps us six games unbeaten and gets us out of the bottom three and finishes off a very good November."