The striker took his tally to four goals in two starts since rejoining Blackpool on loan from Swansea with a fine individual strike and a penalty.
There seemed little danger when Dobbie picked up the ball midway through the first half but he opened the scoring with a superb, jinking run into the penalty area and a neat finish.
And in the second half Dobbie, who scored twice in last week's 3-0 win over Southampton, sealed Blackpool's victory from the spot after Thomas Ince was brought down by Tomasz Kuszczak.
The defeat brought an end to Watford's seven-match unbeaten run which had raised hopes of gatecrashing the play-offs at Vicarage Road.
Blackpool came close to finding the net after just five minutes but were thwarted by Kuszczak.
Ince's shot deflected off Martin Taylor but the on-loan Manchester United keeper got a hand to the ball and then scrambled back to scoop it off the line.
Watford had their chances in the early stages as well, with Sean Murray volleying over and Chris Iwelumo heading wide.
But it was the visitors who went ahead after 25 minutes thanks to Dobbie's superb piece of skill.
The Scot collected the ball 30 yards out and carved his way into the penalty area, tip-toeing his way past the entire Watford defence before coolly stabbing the ball past Kuszczak.
The Hornets attempted to hit back before half-time but Matt Gilks saved from Troy Deeney's header and John Eustace drove wide.
After the interval Watford winger Mark Yeates attempted to replicate Dobbie's effort when he side-stepped a couple of challenges in the Seasiders' penalty area but his run was blocked by Ian Evatt.
Blackpool were forced to make a change on the hour when Gary Taylor-Fletcher suffered an injury and had to be replaced by Barry Ferguson.
Ince had a chance to double their advantage when Neal Eardley crossed from the right but the midfielder was way off target with his volley.
At the other end Eustace tried a cheeky lob with Gilks having wandered off his line but the ball drifted wide.
Instead, Blackpool grabbed the killer second after 70 minutes when Matt Phillips played in Ince, who was tripped as he tried to round Kuszczak.
Referee James Linington pointed to the spot and Dobbie made no mistake to secure another win for Ian Holloway's side as they chase a return to the Premier League.