Their vow comes after seven months of turmoil in the town.
In May, a judge stripped the department of its policing powers after the SBI arrested two officers.
Town leaders still haven't given officers the okay to go back on patrol.
But Monday's ceremony is viewed as a big step in the right direction.
"It's been very trying," Spring Lake Police Dept. Sgt. Mack Utley said. "Everyone has been patient, everyone has jumped through a lot of hoops, but it's nice we can now see the light at the end of the tunnel."
Former Chapel Hill Police Chief Greg Jarvies took over as interim chief in May. His last day is Tuesday.