"I see myself as a physical run stopper," Wilson told reporters after being picked.
"He was kind of a sleeper guy for us," said John Schneider, Seattle's general manager.
Thomas, a 6-4, 330-pound nose tackle, was projected to go as high as the second round, but he was available for the Chargers at the No. 146 overall selection.
"I don't care when I got taken, only that I did," Thomas said. "I was excited just to hear my name called."
"Cam Thomas is a very strong, active player," said Norv Turner, San Diego's head coach.
Undrafted Free Agents: Kyle Jolly (Pittsburgh), Kennedy Tinsley (St. Louis), Aleric Mullins (Green Bay), Bobby Rome (Green Bay), Jordan Hemby (Indianapolis)