Strikes in either half from Dany N'Guessan and Spurs loanee Adam Smith, either side of a Jon Stead equaliser, were enough for the victory that brings the Lions back level on points with sixth-placed Watford.
The hosts were dominant for large spells and spurned a number of chances to put the game beyond doubt. But for Jackett, the result was by far the most important aspect of the afternoon.
"It's great to get a win after two losses, I'm very, very pleased with that," he said.
"Their keeper was far busier than ours and kept them in it with some excellent saves and we're very pleased with the victory.
"We were that dominant in the first half perhaps we could have been further ahead.
"Finishing is such a big part of the game. We could have been further ahead, you know that with the quality of their substitutes that the game is going to turn and they're going to cause you a problem.
"We responded very well after the equaliser and worked their keeper several times.
"I am very pleased for Adam Smith because throughout his Millwall career he has looked like breaking through from the back in either setting up or scoring a goal."