The star made a guest appearance at Zippos Circus to entertain the 300 youngsters, who have all been helped by groups aided by funds from his "Newman's Own" spaghetti sauces and other products.
Dressed in a green bowler hat, outsize bowtie and giant, yellow clown shoes, the 79-year-old star delighted the crowd with his 10-minute slapstick routine, which also involved sitting in a large cream pie.
"I'm not by inclination a clown. This will certainly end my professional career," he joked before the show.
Aptly for a man who starred in the cowboy classic "Butch Cassidy and the Sundance Kid," Newman's name for the occasion was Butch Bolognese.
The actor started the not-for-profit "Newman's Own" in 1982 and has so far donated more than $150 million to charities around the world.
Newman has been nominated ten times for an Academy Award, winning once for 1986's "The Color Of Money." He has also received an honorary Oscar the year before, and the Academy's Jean Hersholt Humanitarian Award in 1994. He also won Best Actor at the Cannes Film Festival in 1958 for "Long Hot Summer."