Senior Madison Mignogna had two goals and senior goalie Maresa Malcolm made four saves for the shutout for second-seeded Haddon Heights (16-4-1).
The Garnets will host third seed Audubon in the sectional semifinals Friday.
Senior Ali LaMaina and junior Amanda Augugliaro played strong games for seventh-seeded Haddonfield (11-10-1), which used three freshmen and four sophomores for long stretches of the game.
"We had some good individual efforts," Haddonfield coach Lindsay Kocher said. "But I think our inexperience showed."
Haddon Heights beat Haddonfield twice in Colonial Liberty play, but both games were competitive and DelCollo was wary of the challenge of beating a team three times in a season.
"That's what I've been telling our girls about Collingswood," DelCollo said of the top-seeded Panthers, who beat the Garnets twice in the regular season.
Haddon Heights took command midway through the first half as Mignogna and Rosati scored in an 84-second span for a 2-0 lead.
Rosati assisted on Mignogna's goal, then added one of her own with a strong individual effort.
"When we work together, we feel like we're unbeatable," Rosati said. "We love the sport. This team means more than anything."
Mignogna added another goal off an assist from Christine Sikora about seven minutes before halftime.
Haddon Heights generated 12 penalty corners to six for Haddonfield, as Rosati moved the ball consistently through the midfield and into the Bulldogs circle.
"She controlled the field," DelCollo said. "Right to the end, she was trying to muscle the ball over the line."
Haddonfield 0 0 – 0
Haddon Heights 3 0 – 3
Goals: HH-Madison Mignogna 2, Jacqui Rosati.
See and hear from Haddon Heights junior Jacqui Rosati.