Stadler was born in San Diego. His father started him in golf at age four, and he displayed a talent for golf early in life. Stadler attended La Jolla High School. He won the 1973 U.S. Amateur, while attending the University of Southern California, where he was a teammate of future PGA Tour winners Mark Pfeil and Scott Simpson. Stadler was an All-American all four years – first-team his sophomore and junior years; second-team his freshman and senior years. Stadler finished college in 1975 and turned professional in 1976.
Stadler won his first two PGA Tour events in 1980, at the Bob Hope Desert Classic and the Greater Greensboro Open. His career year was 1982 when he won four PGA Tour events including The Masters after a playoff with Dan Pohl. Stadler won the B.C. Open in 2003, becoming the first player over age 50 to win a PGA Tour event in 28 years. He won 13 PGA Tour events in all, and played on the 1983 and 1985 Ryder Cup teams.
Stadler began playing on the Champions Tour upon becoming eligible in June 2003. His greatest successes came during his first two years of eligibility. He underwent total left-hip-replacement surgery in Los Angeles on September 15, 2010, which limited his playing time going forward.
Very popular with the galleries, Stadler is affectionately called “The Walrus” for his portly build and ample mustache. He currently lives in Denver, Colorado. His son Kevin is also a PGA Tour champion. Kevin turned professional and won the 2002 Colorado Open in a playoff with his father as his caddie.