Photos and video show he wrote Clark's name along the bottom of each shoe.
Cousins played for the Sacramento Kings for nearly seven years.
He and former Warrior Matt Barnes, who was raised in Sacramento, paid for Clark's funeral.
The Sacramento district attorney announced earlier in the day that the two officers who shot Clark last year will not face criminal charges. The shooting of the unarmed 22-year-old in his grandmother's backyard prompted nationwide protests.