Mark Spitz is a former competitive swimmer. At age nine, he was training at Arden Hills Swim Club in Sacramento with swimming coach Sherm Chavoor, who mentored six additional Olympic medal winners. Spitz held one world age-group record and 17 national records at the age of 10.

Spitz is a nine-time Olympic champion. He was the most successful athlete at the 1972 Summer Olympics in Munich, winning seven gold medals, all in world record time. This was an achievement that lasted for 36 years until it was surpassed by fellow American Michael Phelps, who won eight golds at the 2008 Summer Olympics in Beijing. Between 1968 and 1972, Spitz won nine Olympic golds, a silver, and a bronze, in addition to five Pan American golds, 31 Amateur Athletic Union (AAU) titles and eight National Collegiate Athletic Association (NCAA) titles. During those years, he set 35 world records, two of which were in trials and unofficial. Swimming World Magazine named him World Swimmer of the Year in 1969, 1971, and 1972. He was the third athlete to win nine Olympic gold medals. 

SPitz commentated swimming events at many of the Olympics, including the 2004 Summer Olympics. In a 2019 commercial, Spitz pitched a personal EKG device by KardiaMobile.