Two tries from flying winger Colin McKay and one from centre Sam Berry was enough to see off the stubborn home side.
On a heavy pitch and in front of a hostile home crowd, Paisley worked hard to keep their free-flowing style going and it paid off almost immediately.
Within 10 minutes the forwards had shipped the ball from wide out on the right flank across the pitch to McKay who touched down in the corner.
Martin McKellar added the two extra points from a seemingly impossible angle.
Berry made it 12-0 to the Buddies when he scored in the same corner after some more good work by the forwards.
A magnificent line break by Berry led to a frantic ruck five yards from the Arran try-line.
As both packs battled for possession, Paisley’s back set up to the right in anticipation of a pass, but Berry plucked the ball from the base of the ruck and dived over the line.
Things were looking good at half-time, with Paisley having dominated in the line-outs and coped with Arran’s massive forwards at the breakdown.
But when Arran pulled a try back minutes after the restart, things started to look a little less certain.
A second try for Arran, following some careless defending inside the Paisley 22 metre area, saw the game level at 12-12.
With coach Grant Sweenie and the travelling Paisley support growing restless, the Buddies composed themselves and set about working to the gameplan.
And like it did in the first half, it worked a treat.
Some patient build-up play saw the forwards secure possession for a number of phases before finally the ball was whipped out wide again, with McKay collecting and sliding over the line for the winning score.
Scorer Sam Berry said: “We badly needed that win and thankfully we got it in the end.
“Arran made it difficult, as they always do, but we managed to pull it off.
“We have two games left, both at home, and we need to win them both to have any chance of promotion.
“It would be great to see a big crowd down on Saturday to watch us play Wigtownshire.”
Paisley face Wigtownshire at Anchor at 3pm on Saturday.