The team and league said in a statement that the investigation has been closed, barring new evidence emerging in the future, and noted Tennant declined to participate in the investigation.
"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," the statement said.
More than 20 individuals were interviewed during the investigative process, and "numerous documents and other relevant materials" were reviewed.
Sacramento reaffirmed its commitment to Walton following the conclusion of the investigation.
"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.
Walton noted his focus is solely on the upcoming season moving forward.
"I am 100 percent focused on coaching the Sacramento Kings, and energized to work with this incredible group of players and coaches as we start the preseason," Walton said in a statement. "I will have no further comment."
A civil lawsuit Tennant filed against Walton in April is still ongoing.
Per Jason Anderson of the Sacramento Bee, Tennant said in the lawsuit Walton—who was an assistant coach for the Golden State Warriors at the time he allegedly assaulted her—forced himself onto her in his hotel room. She said that he had pinned her down on the bed and proceeded to kiss and grope her despite her telling him to stop.
She told reporters in April, "I thought he was going to rape me."
According to Anderson, Tennant also said Walton sexually harassed her while he was the head coach of the Los Angeles Lakers, a job he held from 2016 to 2019.
Walton has denied the allegations.
Walton served as an assistant on Steve Kerr's coaching staff in the Bay Area from 2014-16, winning an NBA championship in 2015. He was hired as the head coach of the Lakers in 2016. He spent three seasons in L.A., going 98-148 before the two sides mutually agreed to go their separate ways on April 12.
He was hired by Sacramento on April 15.