The 15-year-old Broomieknowe member stormed to a six-shot success in the 54-hole event after finishing with a four-under-par 209 total.
The triumph, which was sealed by a closing 71 on the Eden Course, followed her successful defence of the Scottish Girls’ Championship at Moray last summer.
“I was really steady out there today,” said Darling, who also won the inaugural Under-16 Girls’ Open at Fulford last year.
“I went on a bit of a par run, but I stuck to my gameplan and I’m just really happy to come away with the win.”
She was able to share the victory with her parents, adding: “It’s the first time that they have both been here to see me win a national title.”
Darling now turns her attention to the Helen Holm Trophy at Troon – a counting event for the Junior Solheim Cup at Gleneagles in September. “Next week’s event is a women’s event but I’m ready to take on the challenge,” she added.
Over in Ayrshire, there was a Welsh win in the Scottish Boys’ Open as James Ashfield capitalised on a dramatic collapse from Ireland’s Eoin Sullivan on the back nine.
Sullivan looked to be in control after carding a four-under-par 67 to take a one-shot lead into his final round before going three-under-par through three holes on the closing circuit.
However, he then limped home in seven-over, opening the door for Ashfield to claim the title by two shots with a seven-under-par 277 total.
Blairgowrie’s Gregor Graham signed off with a 68 to finish joint-second alongside Sullivan and Finland’s Sarkke Siltala.
Graham picked up the George Mcdonald Memorial Bowl as the top under-16 player, saying: “It feels absolutely amazing to be able to win something in your home country, you can’t get much better than that.”