Johnson, Mark Walter and other investors bought the Los Angeles Dodgers in 2012 for a record $2.15 billion. The same group now owns the Sparks, minus Peter Guber, who owns a stake in the NBA's Golden State Warriors.
WNBA President Laurel Richie said Walter, the Dodger's chairman, approached the WNBA about buying the Sparks a few weeks ago. Richie said Walter and Johnson discussed the idea on a cross-country flight and by the time they landed on the West Coast they had decided they wanted to own the Sparks.
The Sparks has been in limbo since Christmas, when owner Paula Madison announced she was ending her involvement. She told The Associated Press that her family had lost $12 million, including $1.4 million last season, operating the franchise since buying it from the Buss family in 2007.
Johnson was a part owner of the NBA's Los Angeles Lakers for a decade before selling his share in 2011.
Though the Sparks hasn't been successful financially, the team has been one of the WNBA's best teams on the court and has led the league in attendance the past two seasons.
They won titles in 2001 and 2002 and made it to the playoffs in five of the past six seasons. They were knocked out in the opening round by Phoenix last season.
The WNBA announced in a statement that the team will remain in Los Angeles and play at Staples Center. The league's 2014 game and television schedule is set to be announced sometime this week.
The Los Angeles Sparks is one of the WNBA's original eight teams.
The Associated Press contributed to this report.