Tseng, 22, defended her British Open title by firing a 3-under 69 in the final round, easily outpacing Brittany Lang, who came on strong with a 5-under 67 Sunday at Carnoustie in Scotland.
The world No. 1 collected her fourth major title earlier this year LPGA Championship. Sunday's victory was her fourth of the year and the ninth career of her LPGA Tour career.
Third-round leader Caroline Masson, playing in only her second major championship, had blown her two-shot lead to Tseng by the sixth hole, ending with a 6-over 78 on Sunday, good for a fifth-place tie.
Sophie Gustafson carded a 4-under 68, grabbing sole possession of third at minus-11, and Amy Yang (67) finished alone in fourth one shot further back.