Arsenal sealed a fourth straight Premiership win but were grateful for some woeful Watford finishing.
Henry celebrates scoring Arsenal's second against Watford
Theo Walcott was handed his Premiership debut after his two midweek goals for England's Under-21's in Germany.
And the Gunners went ahead when Watford's Jordan Stewart put into his own net before Thierry Henry slotted home the second just before the break.
As winless Watford wasted more chances, Emmanuel Adebayor sealed Arsenal's win with a tap-in from Henry's pass.
Before the match started a pitch-side presentation was made to boss Arsene Wenger to mark his 10 years as Gunners boss.
And it set the scene for a mood of celebration at the Emirates Stadium.
It allowed Walcott to settle early and set the pace of the match with some incisive running from the inside left channel.
He first set up Tomas Rosicky, whose crisp shot was well blocked by Watford's Ben Foster before the keeper then got up to brilliantly block the rebounded effort from Adebayor with his legs.
Walcott then slotted a dream ball through for Fabregas, who rounded Foster but failed to slot into an empty net.
But after surviving the early storm, Watford, who have yet to score a Premiership victory this season, carved out two excellent chances to break the deadlock.
Smith collected a poor clearance from Lehmann and fed Marlon King, whose cross was met by Damien Francis at the far post but he saw his effort well blocked.
From the resultant corner, Francis should have put the Hornets one-up but he volleyed over from six yards.
Arsenal continued to push forward and were finally rewarded with the opening goal after 33 minutes.
Febregas's floated free-kick was headed goalwards by Adebayor but deflected into his own net by Stewart under pressure from Kolo Toure.
With Arsenal missing their player-of-the-month for September, Emmanuel Eboue, the hosts certainly looked shaky at times in defence.
But when Henry left two defenders stranded with a cheeky piece of footwork and then fired his shot just inches wide, he clearly signalled his intent to take command.
The Frenchman effectively wrapped the game up in the 43rd minute when he held off Jay Demerit to latch onto a flick from Adebayor and stroked passed Foster.
Arsenal seemed more determined after the break, but clearly looked to be keeping some in reserve ahead of Tuesday's Champions League trip to CSKA Moscow.
Rosicky rifled a fierce drive, which was turned around the post by Foster, before Henry headed just over a minute later.
Walcott was taken off just on the hour mark to a standing ovation as Wenger tightened up his midfield, replacing him with Alexander Hleb.
And the hosts ensured they took maximum points with a goal straight out of the passing text book.
Fabregas slotted through a slide-rule pass to again set Henry free and the striker eased the ball inside for Adebayor to knock home into an empty net.
The Hornets battled on manfully with King, especially, causing the Gunners defence plenty of problems.
But the promoted side were left still searching for their first win in the top flight this season and their first ever Premiership point against the Gunners, who moved up to fourth place in the table.
Arsenal manager Arsene Wenger:
"It was a match against a very good Watford side, who made it very difficult for us at time and we needed a great performance to win. I think we gave that today.
"Overall we did well with the problems they gave us. They are a good team and they look like they can score goals but I was happy with the way we coped.
"Theo Walcott is a young boy, only 17, but he handled his first Premiership start very well and he did well."
Watford manager Aidy Boothroyd:
"I am very pleased we are making chances and I'd be more upset if we weren't creating those. But at this level, if you don't take your opportunities you will be punished.
"We thought we could have upset Arsenal's party but it I was still very proud of my team.
"A lot of teams come here and just lay down but we kept going and created a lot of openings. But against these sort of sides you have to take them.
"This is a whole new level for us and it's only a matter of time before we get that first win."
Arsenal: Lehmann, Djourou, Gallas (Clichy 81), Toure, Hoyte, Walcott (Hleb 64), Fabregas, Silva, Rosicky (Van Persie 74),Adebayor, Henry.
Subs Not Used: Almunia, Song Billong.
Goals: Stewart 33 og, Henry 43, Adebayor 67.
Watford: Foster, Doyley, DeMerit, Shittu, Stewart, Smith (Henderson 45), Mahon, Francis, Bouazza (Powell 54), King, Young.
Subs Not Used: Lee, Mackay, Spring.
Ref: H Webb (S Yorkshire).