Terms of the deals were not released Monday.
Williams has spent most of his four seasons in the NFL with Carolina, playing in 46 games primarily on special teams.
He blocked a key punt last season against the New York Jets, setting up the Panthers in the red zone for a touchdown leading to a Carolina victory. His 28 special teams tackles last season were the second-most on the team since 2010.
Dockery joined the Panthers midway through the 2012 season and has played in 12 games with two starts. He was limited to five games last season due to thumb and shoulder injuries.