Keenan-Bolger was born in Detroit, Michigan. She appeared as a munchkin in the Madison Square Garden production of the Wizard of Oz at 13 years old opposite Roseanne Barr. She has credits in the national tours of The Will Rogers Follies and The Music Man as well as numerous regional credits and college productions at Oberlin College where she graduated from in 2006 with a BA in Theatre and Gender & Woman's Studies with a minor in Comparative American Studies. In 2008, she performed in a special cabaret alongside her two siblings entitled (Keenan-Bolger)³, the first time all three Keenan-Bolgers had performed together on stage in 15 years, to a sold-out house.