Smith accepted the head coaching job at Weber State, his alma mater, about four months ago and it was a surprise when he announced Monday he was moving to Arkansas.
The Arkansas position opened when Razorbacks Coach Bobby Petrino was fired April 10 with cause following the revelation that Petrino had an "inappropriate relationship" with a member of the athletic department.
Sears, 44, was the defensive coordinator at Weber State, taking the position April 2. In addition to being the interim head coach, he will continue to serve as defensive coordinator.
"I'm extremely honored by the opportunity to be in a position to be named interim head coach at Weber State," Sears said. "We have some great things in place here at Weber State and I look forward to working with our team this season."
Sears, who has nearly 20 years of coaching experience, spent the past three seasons at Washington State, his alma mater, as the co-defensive coordinator.