"Some of my greatest lessons in acting, living and being a respectable human being came through James Avery. Every young man needs an Uncle Phil. Rest in Peace," Smith said on Facebook Sunday.
He also posted a picture of the show's cast with a caption that said, "This photo was the last time we were together."
Avery died Dec. 31 from complications following open heart surgery. He was 68.
"The Fresh Prince of Bel Air" ran 1990-96 and is still popular in reruns.