Pettibone's football career started at Jesuit High School in Dallas, Texas. He earned All-State honors as a running back on the state championship football team in 1956 and 1957. He received the honor to be in the first class inducted into the Jesuit Sports Hall of Fame. After graduating from Jesuit High School, Pettibone received a scholarship to the University of Oklahoma, where he played halfback under Bud Wilkinson.