Wolfsburg went a man down just seconds before half-time when Sotirios Kyrgiakos saw red but the hosts held firm and snatched the points when Dejagah fired home on 63 minutes.
The visitors had the first chance of the match after 10 minutes but Dorge Kouemaha's shot did not have enough power behind it to trouble Diego Benaglio in the Wolves goal.
Kaiserslautern nearly scored an own goal in the 38th minute as Rodnei's headed clearance attempt went just inches past his own goal.
The hosts appeared to be up against it when Greek defender Kyrgiakos was dismissed on the stroke of the interval for a professional foul on Itay Shechter, who was through on goal.
The visitors very nearly capitalised from the ensuing free-kick but Christian Tiffert's shot went just wide.
Wolfsburg fended off the visitors' assault early in the second period and went ahead just after the hour when Marcel Schafer crossed from the left and Dejagah was in the right place to head in from four yards.
The hosts nearly doubled their advantage five minutes later but Christian Trasch's long-distance effort was off target.
Wolfsburg had the ball in the net for the second time in the 79th minute but Hasan Salihamidzic's effort was disallowed for offside.
And the hosts missed a final chance to make the margin of victory more comfortable in the 90th minute as Kaiserslautern goalkeeper Kevin Trapp did a superb job stopping Schafer on the counter-attack.