Nordqvist, winner of the 2009 LPGA Championship and the 2017 Evian Championship, finished one shot clear of Georgia Hall, Madelene Sagstrom and Lizette Salas.
The experienced 34-year-old shared the lead with playing partner Nanna Koerstz Madsen heading down the 18th, but a par was enough to secure victory.
Koerstz Madsen hit her second shot into a bunker and then shanked the recovery.
In a nightmare finish, the Dane eventually took a double-bogey six for a share of fifth place on 10-under.
Australian Minjee Lee, winner of the Evian Championship last month, set the early clubhouse target with a 66 for 10-under before Hall (67), Sagstrom (68) and Salas (69) put themselves in contention.
But they fell just short as three birdies on the back nine and another at the par-five 14th after dropping her only shot of the day at the 12th saw Nordqvist home.
World number one Nelly Korda, joint leader after round one, holed a monster putt for a birdie at the 18th, but she could only post a 72 for six under par.
Scottish amateur Louise Duncan also posted a level par round of 72 to finish joint tenth on seven-under par to win the Smyth Salver for best amateur. (AFP)