Kelli Tennant, a former Spectrum SportsNet reporter, sued Walton on April 22, accusing him of sexual assault, verbal and physical harassment and unwanted physical contact over a three-year period.
A day later, Tennant held a press conference and recounted an alleged incident at a Los Angeles hotel in 2014 during which, she said, Walton pinned her to a bed.
At the time of the alleged incident Walton was an assistant coach with the Golden State Warriors.Tennant's lawsuit and news conference came only a week after he was named the Kings head coach.
Her allegations prompted the NBA and Kings to launch a joint investigation. Almost two-dozen people were interviewed during the investigation, but despite "repeated attempts" to interview Tennant, she did not participate on the advice of her legal team, according to an NBA statement.
The statement read: "Based on this and the available evidence, the investigators determined that there was not a sufficient basis to support the allegations made against Coach Walton."
Tennant's civil suit is believed to still be active. Tennant's attorney, Garo Mardirossian of Los Angeles, did not immediately respond to a request for comment by the Sacramento Bee.
Walton, who coached the Los Angeles Lakers for three seasons before parting ways with the team in April, takes over a Kings club that finished 39-43 last season.
"I am 100 per cent focused on coaching the Sacramento Kings and energised to work with this incredible group of players and coaches as we start this preseason," Walton said in a statement on Friday. "I will have no further comment."
"Luke Walton is our head coach and we support him and his team as they continue to prepare for the upcoming season," the Kings said in a statement.