The new deal will keep the 32-year-old at Millwall until the summer of 2013.
“When I was offered a deal I was more than happy to stay and help this club continue to move in the right direction,” Mildenhall told the club’s official website.
“I am disappointed not to have made a first-team appearance but the side have been doing well and so has Dave.
“I’ve got to keep persevering. I’d like to think I have helped get the best out of Dave.”
