Wolves almost got a goal back immediately but Kevin Doyle's looping header clattered off the bar with Bolton keeper Adam Bodgan beaten.
Bolton responded, and De Vries did well to keep his side in the game first to deny Lee Chung-Yong, then minutes later a Marvin Sordell effort.
Doyle tested Bogdan again in the second half when he rose highest in the penalty area, but the keeper was able to beat his effort away from goal.
Bolton upped the ante late on as Sam Ricketts and Craig Davies both had late efforts to kill the game off but neither of them could beat De Vries.
However, Freedman's side held out for the win, keeping their playoff hopes well alive.