Ali, 65, who is debilitated by Parkinson's disease, made a surprise appearance on the Princeton campus, The (Newark, N.J.) Star-Ledger reported. University President Shirley Tilghman praised Ali as a humanitarian and one of the greatest athletes of all time.
Since retiring in 1981, Ali has championed causes from ending world hunger to fighting for elder care and children's rights. President George Bush awarded him the National Medal of Freedom in 2005.
Six others, including award-winning director and choreographer Twyla Tharp, also were awarded honorary degrees by Princeton's Board of Trustees.