Creamer was born in Mountain View, California, and raised in Pleasanton, the only child of an airline pilot father and stay-at-home mother. The family's home overlooked the first tee of the Castlewood Country Club's golf course. Creamer participated in acrobatic dancing and gymnastics during her childhood, and started playing golf when she was 10 years old. At the age of 12, she won 13 consecutive regional junior events in northern California, and the following year she became the top-ranked female junior golfer in California, before moving to Bradenton, Florida in 2000 and enrolling at IMG Pendleton School, a co-educational prep school for athletic students.