Born in London, Umenyiora grew up in his parents' home country of Nigeria before coming to Auburn, where his older sister was attending school. He played two seasons of football for Auburn High School before going to Troy.
"Osi Umenyiora was a 16-year-old high school senior at Auburn High School," former Troy football coach Larry Blakeney said. "An assistant coach there said we needed to take a second look at Osi. We signed him and redshirted him after watching his tape again."
Umenyiora was a part of two Southland Football League Championship teams, helping the Trojans win titles in their final two seasons in the league in 1999 and 2000.