The winless visitors took an early lead at St. James' Park when Will Hughes profited from a fortuitous deflection to fire home.
Fabian Schär's leveller prompted some lengthy spells of pressure from Steve Bruce's men, who were looking for a second Premier League win on the bounce after last weekend’s 1-0 victory at Tottenham Hotspur.
But they couldn’t quite find a second goal against Javi Gracia's resolute defence, who held on to take a share of the spoils.
Barely a minute had been played by the time Hughes bagged the opener, which came after a driving run from Roberto Pereyra and a deflected Tom Cleverley shot. Unfortunately for United, though, it fell into Hughes’ path as he arrived in the box, and the finish was low and decisive.
Bruce’s side looked to hit back immediately and when the impressive Christian Atsu’s cross dropped at Miguel Almirón’s feet it looked for a moment like an equaliser was imminent, but goalkeeper Ben Foster was quick off his line to slide in and whip the ball away from the Newcastle forward.
Almirón’s speed caused some early problems but the second real opening was created by Watford, with Andre Gray bringing the ball down in the area and dragging a shot wide of Martin Dúbravka’s upright.
Jetro Willems, on his first Premier League start for the club, saw a volley blocked and an Almirón breakaway - which left him one-on-one with Foster - was halted by the offside flag, but just before the break the hosts finally found a way through. Schär started the counter-attack and carried on running when the ball was played wide to Emil Krafth. Isaac Hayden met the Swede's cross from the right, but the ball dropped invitingly for Schär, who swept home in front of the Leazes End.
After the break, the Swiss international met Sean Longstaff’s free kick but couldn’t direct his header towards goal and, after Jamaal Lascelles’ fine charge forward from the back, Almirón met Atsu's cutback with a shot which was blocked on its way to goal.
United were gradually turning the screw, and Hayden was next to try his luck, stinging Foster's fingertips with a swerving drive. Then Longstaff had a go, a low, well-struck effort which was held by the former England stopper, while Willems saw his inviting low centre just evade his teammates in the box.
Watford had their moments, with Abdoulaye Doucoure driving run causing some panic and forcing an important intervention from Dúbravka and substitute Isaac Success’ header drawing a vital stop from the Slovakian, while Cleverley's drive took a deflection and fizzed just wide.
Pereyra then forced another save from the Magpies custodian with five minutes to go, before Yoshinori Muto – sent on from the bench after his goalscoring outing in the Carabao Cup defeat to Leicester in midweek – struck the sidenetting with what proved to be the final chance of the contest.
