Civil rights attorney Ben Crump rallied the large group of supporters to demand justice for McClain. The 32-year-old was shot and killed by a Pasadena police officer last August as he ran from officers after a traffic stop.
"I pray, greater Los Angeles County, that we can all tell these babies that we stood up and we said his name -- Anthony McClain -- because Anthony McClain's life matters," Crump told the crowd.
Members of Black Lives Matter and George Floyd's brother, Philonise Floyd, joined McClain's family at Monday's protest.
Pasadena Police Chief John Perez released police videos of the shooting following the traffic stop and said the fleeing McClain could be seen holding a gun in his waistband as he bolted from the passenger seat of the car, and that he then held it in his left hand as he ran.
New bodycam video shows fatal officer-involved shooting in Pasadena
His family says he ran because he was afraid of police and are demanding the officer who fired the fatal shot be fired from the department.
McClain's father has sued the city of Pasadena and several of its police officers, alleging wrongful death and civil rights violations.
Attorneys for Archie Barry, McClain's father, allege the fleeing man was holding his belt buckle and that a gun recovered across the street was not tied to him and was "planted" by officers. A gun is not clearly visible in the video footage released by the police department, but McClain is seen with his hand at his waist as he begins to run.
McClain leaves behind two sons and a two-year-old daughter.
Vigil held for man who died in Pasadena officer-involved shooting
Vigil held in Pasadena after man shot, killed by police during traffic stop
City News Service contributed to this report.