Butterfield seized on an accurate pass by Craig Davies to tap home in the first half, with Vaz Te sealing victory from the bench after winning a one-on-one with Clarets goalkeeper Lee Grant.
Eddie Howe's team find themselves in 17th place in the npower Championship table after a second consecutive defeat banished memories of a four-game unbeaten run.
The Clarets created the early opportunities, Ross Wallace slamming the ball against Stephen Foster on the goal-line, before Junior Stanislas released Kieran Trippier on the right wing.
The Manchester City loanee, who spent last season at Oakwell, dithered and surrendered possession to the marauding red shirts.
The Tykes' lack of cut and thrust in the early stages almost cost them dearly when Stanislas slid an early cross towards the onrushing Charlie Austin, who slipped in the Yorkshire rain and failed to connect.
Danny Drinkwater then emerged as Barnsley's bright spark. His determination to keep the ball at his feet, coupled with expansive trickery and a neat turn of pace, opened space for Butterfield to find Jimmy McNulty lurking in space.
The Liverpool-born defender leapt to connect with the inswinging cross but nodded wide.
But the new slick and ominous home offensive paid dividends in the 21st minute. Davies weaved down the left wing to supply Butterfield who happily tucked home his fourth league goal of the season.
The Clarets broke immediately following the restart, but Jay Rodriguez rattled a powerful effort against the crossbar.
As the rain abated, so Burnley's star began to rise once more. Skipper Chris McCann pinged the ball agonisingly wide of goal after good work from Stanislas and Drinkwater was forced to block a hearty drive from Trippier.
Then 10 minutes before the break, Drinkwater forced Grant to parry his wickedly curving free-kick. The ensuing clash of heads between the Clarets goalkeeper and David Edgar caused hush in the stadium as both received treatment in the six-yard box.
The Tykes twice spurned excellent chances to double the advantage immediately after the break. A moment of confusion allowed Davies a one-on-one with Grant, but he slid the ball across the goalmouth and wide.
And Butterfield had time and space to add a second moments later, forcing an aerial save from Grant with a snapshot when both sides of the net were gaping.
Home goalkeeper Luke Steele was finally called into action on the hour mark. Wallace hit a speculative drive from 30 yards which the former Manchester United stopper could only deflect with his forearms.
Soon Rodriguez had the crowd on their feet when he spotted Steele off his line. On his 100th appearance in a Burnley shirt, his looped effort from 30 yards bouncing in front of the visiting supporters.
Portuguese forward Vaz Te entered the fray in place of Davies and made an almost immediate impact.
With 81 minutes played, the ex-Hibernian men pounced on a sublime through-ball from Gray, before snaking towards Grant and firing low and hard into the net.
The Clarets were firmly subdued as Keith Hill's charges tightened up their dominant midfield to control out the final phases and climb to 15th place in the league table.