Lady Gaga, Meryl Streep and Sigourney Weaver attended Wednesday's amfAR gala to raise money to fight HIV/AIDS and honor Richardson, who died in a skiing accident last March.
Richardson became a champion for HIV/AIDS research after her father, director Tony Richardson, died of it in 1991.
Brooke Shields was overcome with emotion on the red carpet and struggled to articulate her feelings for her friend, whom she described as a beautiful woman and brilliant mother.
Streep sang an a cappella Irish number. Lady Gaga performed "Future Love" while covered in pearls and white body paint.
Richardson's mother, actress Vanessa Redgrave, described Richardson's advocacy as her life's mission.
