She is a member of the Oromo ethnic group from the high-altitude Arsi Zone of the Oromia Region. She is the third child of six, her younger sisters Tirunesh and Genzebe are also international long distance athletes, and brother Dejene is marked as a future star. Like her sister Tirunesh, her cousin Derartu Tulu is a double Olympic gold medalist (1992 and 2000).
Ejegayehu made her debut over the marathon distance at the 2011 Chicago Marathon and, even though she was well-beaten by Liliya Shobukhova (who became the second fastest woman ever), she eventually was ruled the winner after Shobukhova was retroactively disqualified for doping. Her win was the third fastest marathon debut with her time of 2:22:09 hours.