The 20-year-old was already contracted for 2020, meaning his new deal will see him through to the end of the 2021 season.
Vandermeer was selected with the 37th pick in the 2018 AFL Draft, and played 15 matches for Footscray in the VFL this year.
“It shows the Club has a lot of trust in me and also gives me confidence going into the 2020 season to just play with freedom and give it everything,” Vandermeer told the club’s website.
“Getting drafted to the Bulldogs is the best thing that’s happened to me. It’s a very comfortable environment.
“It’s good to head into my second season feeling fit and fresh. I had a few injuries last year, which was a good learning curve, needing to be resilient and work through them.
“Continuity is my biggest goal now. Staying on the track for the whole pre-season will hopefully give me the best chance to play senior footy next year.”