"I am happy for Kliff," Helton said, according to The Athletic's Antonio Morales. "Any time you get an opportunity to be an NFL head coach, it is special. He is a talented coach, that's why we brought him here. I wish him nothing but the best."
Kingsbury was hired as USC's offensive coordinator on Dec. 4 after being fired from Texas Tech following six seasons as head coach.
The Trojans will now be on the lookout for a new OC.
"USC has always attracted the best coaches in the country from all levels," Helton said. "We will spend the upcoming weeks finding the best possible fit for USC and our program."
Before meeting with the New York Jets and the Cardinals, it was reported that the Trojans were blocking NFL teams from interviewing Kingsbury.
The 39-year-old coach reportedly owes USC a $150,000 buyout in order to resign and take the Cardinals' head coaching job, according to NFL.com's Ian Rapoport.