Massaro, 31, who took time out after suffering from fatigue in February, beat New Zealand's Joelle King 11-6 11-2 11-7 in Hull.
England's Nick Matthew is in the last four of the men's event.
The 34-year-old, seeking a fourth title, beat Frenchman Mathieu Castagnet 11-7 11-7 11-7.
Massaro will play defending champion and world number one Nicol David, after the Malaysian beat England's Sarah-Jane Perry 11-6 11-8 12-10.
Matthew's preparation had been interrupted by an ankle injury, but he was pleased with his performance which sets up a semi-final against world number one Mohamed Elshorbagy.
"I guess if you'd offered me a place in the semi-finals before the tournament I'm sure I would have taken it because it means I would have been feeling healthy," he said.
Colombia's Miguel Rodriguez plays Gregory Gaultier of France in the other men's semi-final, while in the women's competition, Camille Serme of France will meet Delia Arnold of Malaysia.
England's former world champion Laura Massaro is through to the semi-finals of the British Open in her first tournament after a break from squash.