"I kiss the ground she walks on," the actor, 57, told PEOPLE at the InStyle/Warner Brothers afterparty. "I adore her."
The double Oscar-winning actress, 50, who has supported Gibson through his dark times, brought many in the ballroom to tears with her emotional speech in which she opened up about her personal life, including her sexuality.
"If you had to fight for a life that felt real and honest and normal against all odds, than maybe you too would value privacy above all else," said Foster, who has been in the spotlight since she was 3.
"I thought [her speech] was great," he said. "I love her."
Gibson, who called his longtime friend's support of him "so flattering," shared why he thought Foster was so deserving of the Cecil B. DeMille Award and outpouring of support at her revelation.
"Because she's real," he said simply.