The Scot holed her birdie attempt at the 18th to earn victory in the afternoon fourballs and help Elaine Radcliffe’s team to a three-point lead at 4½ to 1½ over the USA – their biggest ever advantage after day one.
Darling had been paired alongside fellow Scot Louise Duncan in the morning foursomes where they shared the point with US duo Rose Zhang and Rachel Heck.
She then teamed up with England’s Annabell Fuller for the afternoon fourballs and after starting the 18th all square against Heck and Emilia Migliaccio, Darling made sure of the win with an 18-foot putt for birdie.
Meanwhile, Scott Jamieson is the leading Scot as England's James Morrison set a new course record with a stunning round of 60 on day one of the Omega European Masters.
Morrison made the most of ideal conditions for the early starters to record an eagle, nine birdies and a solitary bogey to finish 10 under par, three shots clear of compatriot Marcus Armitage and France's Robin Sciot-Siegrist.
An eagle on the par-five ninth, his final hole, would have given Morrison the second 59 in European Tour history, but the 36-year-old narrowly failed to hole his pitch from short of the green and had to settle for a tap-in birdie.
Jamieson is tied for 19th after an opening round 67 at Crans-sur-Sierre GC in Switzerland with his three under par scorecard featuring seven birdies, two bogies and a disappointing double-bogey finish at the 18th.