Robert Charles Lee, 40, was convicted of 35 charges, including 9 counts of forcible rape and 14 counts of forcible oral copulation.
Lee attacked his victims in their homes and often terrorized them with a knife. One woman was attacked twice in a matter of months. Most of the victims were between 55 and 75 years old.
Prosecutors say DNA samples from assaults in Los Angeles, Gardena, Carson and Brea led to a single suspect, Lee.
Defense attorney Patricia Green argued some victims described their assailant as a male Hispanic, or shorter than 5'7", while Lee is black and 6'1."
Lee's crime spree spanned almost a decade, until he was arrested in 2006. He faces more than 300 years to life in prison when he is sentenced April 13.
The Associated Press contributed to this report.