Ellen Ostrom was born in Portland, Oregon. She began her dance training at the age of eight with Haydée Gutiérrez, Elena Carter, and James Canfield at the School of Oregon Ballet Theatre in Portland, Oregon. Ms. Ostrom entered the School of American Ballet (SAB), the official school of New York City Ballet, in the fall of 2000. In October 2002, Ms. Ostrom became an apprentice with New York City Ballet, and in February 2003 she joined the Company as a member of the corps de ballet.

Ms. Ostrom is also a 1998 Princess Grace Dance Fellowship nominee.