Tom Cleverley's winner helped 10-man Watford extend their good start to the Championship season and end Burnley's unbeaten start under Vincent Kompany.
The hosts led with the game's first effort on target just before half-time as Joao Pedro's neat touch freed Ismaila Sarr, whose pull-back found Cleverley to side-foot into the bottom corner.
Josh Brownhill was twice denied by smart saves from Hornets goalkeeper Daniel Bachmann as the Clarets improved after the break.
The hosts lost full-back Hassane Kamara to a straight red card for pulling back Vitinho as he bore down on the penalty area, and Brownhill then turned the Brazilian's cross against the bar, but Watford held out.
Watford were without striker Emmanuel Dennis, who is in talks with Nottingham Forest after the clubs agreed a £20m fee for the Nigerian earlier on Friday, but move top of the table going into Saturday's matches.
Both sides went into the game having made the same start after relegation from the Premier League, following up opening-day 1-0 wins with a 1-1 draw.
And Watford boss Rob Edwards can thank a string of late saves from Austria keeper Bachmann - as well as the woodwork - for continuing his 100% Vicarage Road record.
Burnley boasted 70% possession from their opening two games under Kompany, and again had the lion's share of the ball in a feisty opening, but a misplaced pass from goalkeeper Arijanet Muric almost gift-wrapped an opening for Sarr.
Watford gave a debut to Hamza Choudhury, two days after his move from Leicester, and stepped things up after the mid-half drinks break.
And their improvement was underlined when Cleverley marked his 33rd birthday with a first goal since January 2021, before his celebrations - and match - were cut short by a knee injury picked up in scoring.
Kompany made a double change just after the hour, including a debut for winger Nathan Tella, little more than 24 hours after completing a loan move from Southampton.
Burnley's threat grew as Watford were pushed back, Bachmann twice denying Brownhill and then Luke McNally's side-footed volley deep into stoppage-time.
Having won just two home games last season during their Premier League struggles, Watford have now matched that total just 12 days into their return to the Championship.
Line-ups
Watford
Formation 4-2-3-1
1Bachmann
3Pérez Martínez31Sierralta15Cathcart14Kamara
39Kayembe4Choudhury
23Sarr8Cleverley12Sema
10João Pedro
1Bachmann3Pérez Martínez31Sierralta15Cathcart14KamaraBooked at 81mins39Kayembe4ChoudhurySubstituted forKabaseleat 82'minutes23SarrSubstituted forBayoat 64'minutes8CleverleySubstituted forGoslingat 45'minutes12Sema10João PedroSubstituted forAsprillaat 79'minutesBooked at 88minsSubstitutes
2Ngakia9Manaj16Gosling18Asprilla19Bayo26Hamer27KabaseleBurnley
Formation 4-3-3
49Muric
14Roberts5Harwood-Bellis3Taylor29Maatsen
24Cullen8Brownhill26Bastien
17Manuel10Barnes44Costelloe
49Muric14Roberts5Harwood-Bellis3Taylor29Maatsen24CullenSubstituted forMcNallyat 90+1'minutes8BrownhillBooked at 85mins26BastienSubstituted forda Silvaat 75'minutes17ManuelSubstituted forTellaat 62'minutes10BarnesSubstituted forRodríguezat 62'minutes44CostelloeSubstituted forCorkat 45'minutesSubstitutes
4Cork6Egan-Riley9Rodríguez15Peacock-Farrell21McNally22da Silva23TellaReferee:Thomas BramallAttendance:19,225Live Text
Match ends, Watford 1, Burnley 0.
Second Half ends, Watford 1, Burnley 0.
Attempt saved. Luke McNally (Burnley) right footed shot from the centre of the box is saved in the centre of the goal. Assisted by Ian Maatsen.
Hand ball by Jay Rodríguez (Burnley).
Josh Brownhill (Burnley) hits the bar with a right footed shot from the centre of the box. Assisted by Vitinho with a cross.
Substitution, Burnley. Luke McNally replaces Josh Cullen.
Offside, Burnley. Connor Roberts tries a through ball, but Jay Rodríguez is caught offside.
Yáser Asprilla (Watford) is shown the yellow card.
Ian Maatsen (Burnley) wins a free kick on the left wing.
Foul by Yáser Asprilla (Watford).
Foul by Josh Cullen (Burnley).
Edo Kayembe (Watford) wins a free kick on the right wing.
Josh Brownhill (Burnley) is shown the yellow card for a bad foul.
Foul by Josh Brownhill (Burnley).
Dan Gosling (Watford) wins a free kick in the defensive half.
Corner, Burnley. Conceded by Daniel Bachmann.
Attempt saved. Josh Brownhill (Burnley) right footed shot from outside the box is saved in the top right corner.
Substitution, Watford. Christian Kabasele replaces Hamza Choudhury.
Hassane Kamara (Watford) is shown the red card.
Vitinho (Burnley) wins a free kick in the attacking half.