Abi was born in Tampa, Florida. At 12 years old, after her first professional audition, she booked the role of Cindy Lou Who in How the Grinch Stole Christmas the Musical at Madison Square Garden and moved to NYC thus began her professional career.

She and her sister, Milly Shapiro, after their Broadway debuts, created a sister-duo cabaret, which they called "The Shapiro Sisters." They were the first minors to write and perform their own show at 54 Below in NYC.

Throughout high school she trained intensely in ballet at the Joffrey Ballet School. After she graduated high school, she attended Fordham University as a theatre major on the performance track. She left when she was cast as Dorothy Spinner in Doom Patrol season 2.