Half-centuries from Mark Wallace and Tom Maynard helped end Glamorgan's two-year wait for a victory in the Natwest Pro40 competition in emphatic style.
Wallace (85) and Maynard (65) shared a stand of 108 in 18 overs to rescue a Glamorgan innings that had been teetering on the brink of collapse.
Glamorgan were in trouble at 43-4, but Wallace and Maynard helped their side reach a decent total of 216-7.
Surrey could only reach 138 in 33.2 overs as they lost by 78 runs.
Glamorgan won the toss and elected to bat, but opening pair David Hemp and Richard Grant both departed for single-figure scores.
Michael Powell smashed Glamorgan's only two boundaries in the first 12 overs of their innings before he was bowled by Jade Dernbach for 23, while Jamie Dalrymple was trapped lbw for a 17-ball duck.
But Wallace and Maynard started to rebuild, and helped their side get back on track and reach a respectable total.
Surrey suffered an early setback, losing Scott Newman to the second ball of the innings, while James Benning made a quick-fire 28 before being bowled by Jason Gillespie.
Mark Ramprakash departed soon after to leave Surrey at 45-3 and Usman Afzaal could only make 10 as Robert Croft struck with his first ball.
Croft then accounted for Jon Batty, and the tail was quickly wrapped up as Glamorgan wrapped up the win with ease.
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