Manchester City loanee George Evans scored on his debut as Walsall recorded their first league victory at Barnsley in over 44 years.
The 20-year-old midfielder fired the Saddlers ahead just past the hour mark with a low right-footed drive.
And ex-Barnsley winger Milan Lalkovic sealed a comfortable win when he coolly slotted home with 20 minutes remaining.
Dean Smith’s men remain second in League One and are now unbeaten in seven away league matches this season.
The Saddlers showed four changes to the side beaten 2-1 by Chesterfield at the weekend.
New loan signing Evans was thrown straight in, while Craig MacGillivray, Anthony Forde and Lalkovic were also handed starts.
Reece Flanagan dropped to the bench, with Neil Etheridge, Sam Mantom and Andy Taylor missing out through injury.
Despite having lost their previous three matches, Lee Johnson’s Barnsley made the brighter start and threatened first inside two minutes.
Simeon Jackson’s pass deflected fortuitously to Sam Winnall but, leaning backwards, the former Scunthorpe striker scuffed his 14-yard effort wide.
Walsall, who were searching for their first league win at Oakwell since April 1971, soon settled into a passing rhythm.
Romaine Sawyers saw a low shot charged down before Evans bent a speculative long-range attempt straight at Tykes keeper Nick Townsend.
The latter went close again on 19 minutes, when he fizzed a crisp low strike inches wide of Townsend’s near post.
Although goalmouth incident was in short supply, the visitors were displaying more attacking endeavour.
Townsend raced off his line to gather bravely at Sawyers’ feet, and an off-balance Tom Bradshaw fired wide from an acute angle.
On 38 minutes, Bradshaw flicked an effort goalwards from Forde’s cross, with the ball deflecting off Lewin Nyatanga and dropping narrowly wide.
The hosts had barely threatened but went close before the break, Winnall with a rasping 25-yard drive which was beaten away by MacGillivray.
HALF-TIME: BARNSLEY 0-0 WALSALL
Barnsley began the second period on the front foot, with captain Alfie Mawson nodding wide from a corner.
And the Tykes would have taken the lead on 55 minutes but for an expert reaction save from MacGillivray.
Josh Scowen's corner was glanced on by Marc Roberts for Nyatanga to power a far-post header towards goal.
But MacGillivray came to the Saddlers’ rescue, stretching out his right hand to brilliantly claw the ball away.
That save proved even more significant as Walsall made the breakthrough just seven minutes later.
Lalkovic headed Forde’s cross down to Evans, who brought the ball under control before drilling a right-footed effort into the bottom corner.
Barnsley almost hit back immediately, Nyantanga with a flicked header which looped over MacGillivray but bounced back off the bar.
Yet, just moments later, the Tykes fell two goals down as a familiar face came back to haunt them.
Lalkovic, who spent last season with Barnsley, collected Sawyers’ incisive pass ahead of Nyatanga and calmly slotted past Townsend from 16 yards.
The game was now beyond the home side, who had Townsend to thank for not losing by more.
In the closing stages, the home keeper kept out Evans’s drive and then blocked Bradshaw’s six-yard snap-shot with his legs.
FULL-TIME: BARNSLEY 0-2 WALSALL
Team: MacGillivray, Demetriou, Downing, Chambers, Bradshaw, Sawyers, Forde (Morris 78'), Henry, Lalkovic (Cook 83'), Preston, Evans (Flanagan 84').
Subs not used: Jezeph, Baxendale, Bakayoko, Kinsella.