Johnson was born in September 10, 1963 in Walnut Creek, California. He completed his high school education from Livermore High School, where he was a star in basketball as well as baseball. He was drafted by Atlanta Braves in 1982.
Johnson was drafted by Montreal Expos in 1985. He made his major league debut with Montreal Expos in 1988 against Pittsburgh Pirates, in which his team were victorious. After spending a year with Montreal Expos, Johnson signed for Seattle Mariners in 1989. He played for them till 1998. In 1990, he became the first left-handed pitcher to strike out Wade Boggs, three times in one game. Johnson had a good time with Mariners. In September 1992, Johnson struck out 18 batters in 8 innings by throwing 160 pitches against Texas Rangers. This record has not been surpassed by any one in a MLB game till now. Johnson had his career's 1000th strikeout in 1993, in a match against Minnesota Twins. In 1998, Johnson moved to Houston Astros. He had a 10-1 record in 11 regular-season starts with Houston Astros. He helped Houston to win their second National League Central division title. Johnson was again on the move in the year 1999. He moved to Arizona Diamondbacks after spending a year with Houston. Johnson led the team to the playoffs in his first year. In 2001, while playing against Cincinnati Reds, he struck out 20 batters in a game. In the same year in a match against San Francisco Giants, Johnson threw a fastball to Calvin Murray that killed a bird in the pitch. Johnson won prestigious Triple Crown in 2002. The year 2003 for him was hampered with injuries. He pitched the 17th perfect game in baseball history in 2004. Johnson played for New York Yankees from 2005-2006. He was inconstant during his time with the Yankees. After playing with Yankees for a year, he returned back to Arizona Diamondbacks in 2008. Johnson joined San Francisco giants in the year in 2009 and announced his retirement from professional baseball in 2010. Johnson has also appeared in some movies and TV commercials.
Johnson is a married man. He has a daughter from his first relationship. There are not much news about his first relationship. In 1993, Johnson married his girlfriend Lisa Wiehoff, with whom he shares 4 children. His relationship with Lisa is going well and there are no news of their divorce. He is a father of total 5 children.
Johnson was a very successful player, standing 6 ft. 10 inches tall. He was one of the tallest as well as talented players ever to grace the MLB. His weight during his playing career was about 102 kg. During his career as a player, he has won 5 Cy Young Awards, 1 Triple Crown, 4 ERA champion awards, 9 Strikeout champion awards and several other honors. He was included in All-star team for 10 times. He was elected to the Baseball Hall of Fame in 2015. Johnson has an estimated net worth of almost $115 million. His exact salary amount is unknown, however it is a known fact that he had signed some huge money deals in his playing career.