Ballmer officially takes control of LA Clippers
A view of the court during the game between the Brooklyn Nets and the Los Angeles Clippers at the Staples Center on November 16, 2013 in Los Angeles, California - by Stephen Dunn
Ballmer said he was "humbled and honored" after the transaction was sealed when a California court order went into effect confirming that Shelly Sterling had the authority to sell the team.
The team went on the block after the NBA slapped a life ban on her estranged husband and its owner, Donald Sterling, who bought the club in 1981 for $12.5 million.
The action was in response to a video aired on celebrity website TMZ that showed Donald Sterling criticizing his girlfriend for having her picture taken with black people.
In the storm that followed, the 80-year-old billionaire initially agreed to the sale of the team, but then abruptly withdrew his support.
His wife Shelly, however, moved to sell the Clippers as a trustee of the family trust that owned the team after Sterling had been declared mentally incapacitated.
The NBA Board of Governors had previously approved the sale and Ballmer now takes on the title of Clippers Governor.
Ballmer thanked Clippers fans for remaining "fiercely loyal to our franchise through some extraordinary times."
"I will be hardcore in giving the team, our great coach, staff and players the support they need to do their best work on the court," he said.
"And we will do whatever necessary to provide our fans and their families with the best game-night experience in the NBA."
- 'Wonderful new owner' -
Ballmer is expected to travel to California later this week and have dinner with head coach Doc Rivers and the players, then meet with Clippers employees and fans at an event next Monday.
Rivers said they can now focus on winning a first title.
"This is an amazing new day in Clippers history," Rivers said. "I couldn't be more excited to work together with Steve as we continue to build a first-class, championship organization.
"I am already inspired by Steve's passion for the game, his love of competition and desire to win the right way, and I know our players and fans are going to be inspired as well."
Ballmer's purchase would make the Clippers the second most expensive franchise in US professional sports. It is the highest price ever paid for an NBA team.
On July 28, after a three-week trial, Judge Michael Levanas gave the green light to the sale, finding no evidence of a secret plot against Sterling.
Sterling contended he had been duped by his wife into submitting to the medical tests as part of a plot to have him ousted from the trust so the sale could move forward.
Donald Sterling appealed the decision to a court in Los Angles, but it was rejected.
"I am thrilled that the Clippers now have such a wonderful new owner," Shelly Sterling said. "I am happy for the team, the fans, the sponsors and the city of Los Angeles.
"I am confident that Steve will bring the city a championship team in the very near future. I cannot wait for the new season to begin."
Donald Sterling has said he would not go down without a fight and still is reportedly expected to launch another appeal of the sale.
The decision to hand the team over to Ballmer comes one day before the NBA is expected to announce its new schedule.