After a goalless first half, the Eagles sealed another victory thanks to strikes from Tom Soares and James Scowcroft at either end of the second period, to move within a point of the top six.
That combination carved out the first chance of the afternoon, but Tykes' loan goalkeeper Luke Steele made a fine diving save to deny Scowcroft.
Soon after Palace had an escape when Kayode Odejayi blasted over from close range after Soares had blocked the striker's first effort from Brian Howard's corner on the goal-line.
The rest of the first half saw little goalmouth action, although the visitors should have broken the deadlock just after the half-hour mark when Odejayi pulled the ball across the face of goal for strike partner Istvan Ferenczi.
However, the Hungarian scuffed his close-range shot and Eagles keeper Julian Speroni was able to make the save.
Within a minute of the restart, Neil Warnock's side hit the front as Soares latched on to a loose ball and sent his low shot beyond Steele and into the back of the net.
Jon Macken spurned a chance to grab an equaliser soon after, before Ben Watson touched Shaun Derry's shot against an upright as Palace went in search of a clinching second goal.
Scowcroft then saw two openings snuffed out by the impressive Steele, as the Tykes began to come under heavy pressure from the home side.
However, there were only seven minutes left on the clock when Palace made the game safe. Matt Lawrence's header was touched on by Soares and Scowcroft found just enough space to squeeze a left-foot shot past Steele to record the 100th goal of his senior career.