A graduate of San Diego State University where he also played basketball and set a school record for assists, Gwynn broke in with San Diego as a part-time outfielder in 1982, appearing in 54 games and batting .289. It would be the last time he would hit below .300 in the major leagues. Gwynn's breakthrough season was in 1984, when he batted .351, won the first of his eight batting titles (tying him with Honus Wagner for the National League record), and made the first of his 15 All-Star appearances.
Nicknamed "Captain Video" because of the extensive collection of videotapes he kept, Gwynn constantly studied his swing to improve his hitting.
Gwynn was also proficient with a glove for most of his career, winning five consecutive Gold Glove awards from 1986 to 1991. Primarily a right fielder, Gwynn split time between right and center field in 1989. In 1994, Gwynn batted .394, the highest batting average in the National League since Bill Terry hit .401 in 1930 and the highest in the majors since Ted Williams hit .406 in 1941. Had the season not been shortened by a strike, Gwynn might have become the first batter to eclipse .400 in more than 50 years.
Gwynn retired in 2001 with a total of 3,141 hits and a lifetime batting average of .338. He played his entire career with the Padres, a rarity in the 1980s and 1990s. He becomes eligible for induction into the Baseball Hall of Fame in 2007.
After his retirement, Gwynn became an analyst for ESPN and head baseball coach at his alma mater, San Diego State. SDSU's baseball stadium, which he largely funded personally, is named for him.
Gwynn's brother, Chris Gwynn, was an outfielder for the Los Angeles Dodgers and Kansas City Royals.