He was born and raised in Houston, Texas, where he became one of the first graduates from Willowridge High School in 1981. At one point he dreamed of a professional football career, but later served in the United States Air Force and dreamed of becoming "the second "General Washington."
He settled on acting, however, and attended Howard University as a Theater Arts major. After college, he became an original member of the City Kids Repertory, a theater company that performed in schools in effort to bring relevant productions to inner-city youths.
Washington has guest starred on Law & Order, NYPD Blue, Ally McBeal and other TV series. His film credits include Girl 6 (1996), Get on the Bus (1996), Out of Sight (1998), True Crime (1999), Romeo Must Die (2000), Exit Wounds (2001) and Ghost Ship (2002).
His full name is Isaiah Washington IV. A DNA test to determine his heritage showed that his father's side is from Angola and his mother's side is from Sierra Leone. He married Jenisa Marie Washington on Valentine's Day, 1999. They have two children.