Mark Robins' side hit the post twice in a matter of second-half minutes as they pushed for a deserved winner but could not find a way through as the Hornets held on.
The Tykes remain in midtable, although only three points short of the play-off spots, while the visitors are a further two points back.
Watford started strongly with on-loan Birmingham midfielder Jordon Mutch registering the first effort on target with a low drive which was well held by Luke Steele.
The promising opening soon fell flat however as both sides struggled to create in the final third.
Barnsley's chief attacking threat this season has been former Liverpool winger Adam Hammill and after an anonymous opening half hour he burst into life.
He cut inside to thump a 30-yard drive into the midriff of Watford's England Under-21 goalkeeper Scott Loach before repeating the trick moments later to send another powerful drive just over the top.
Mutch then saw another effort at the other end blocked by Tykes centre-half Jason Shackell before Barnsley striker Garry O'Connor fired over the top.
Malky Mackay threw on Marvin Sordell at the start of the second half as the visitors looked to find a cutting edge but it was Hammill who nearly broke the deadlock just after the hour mark.
Hammill was fouled by Watford midfielder Stephen McGinn on the edge of the area and curled the resulting free-kick around the wall and past Loach only to see the ball bounce away off the far post.
The home side were on top and incredibly hit the woodwork again 90 seconds later.
Hammill's corner was cleared by Adrian Mariappa and Jacob Butterfield lashed in a left-footed strike from the D which again beat Loach but hit the frame of the goal.
Robins introduced Paul Hayes in an attempt to press home their superiority and the on-loan Preston man was straight into the action.
Jim O'Brien beat his man on the right-hand side and crossed for Hayes but the striker could not direct his header into the corner and Loach held on.
O'Connor and Hayes both fired wastefully over from long range in a tense finale before Stephen Foster wasted the last chance for the hosts deep into stoppage time when he rose well to head Kieran Trippier's free-kick over the top.