DeCamillis, 47, on the Cowboy's staff for four years, will also be the Bears' special teams coordinator, the Fort Worth Star-Telegram reported Thursday.
"It's one of the great franchises in the league," he said of his new employer. "I'm hoping I can help any way I can and hopefully add to it."
In Chicago, DeCamillis replaces Dave Toub, who will join new Kansas City Chiefs Coach Andy Reid.
DeCamillis will work under Marc Trestman, who was introduced as the new Bears head coach Thursday, replacing Lovie Smith, who was fired.