He died last week at 57 after a battle with cancer.
Mitchell served Rainbow PUSH for decades as the Rev. Jesse Jackson Sr.'s right-hand-man.
There's a memorial service for him on June 28.
Visitation is from 2 to 3 p.m., and the service is from 3 to 4 p.m. at Trinity United Church of Christ, located at 400 W. 95th St.
Then, Rainbow PUSH is celebrating Mitchell's life and legacy from 10 a.m. to noon June 29 at its headquarters, located at 930 E. 50th St.
"We already miss John's ubiquitous presence and tremendous voice within our organization," the organization said in a statement Wednesday.