The 21-year-old was due to fall off-contract at season's end and was attracting interest from clubs in Melbourne.
But Bergman has recommitted to the Power, currently second on the ladder and on a club-record 11-game winning streak.
"I've got some great friends at the club and we're really tight as a group," he said on Thursday.
"Everyone can see how much potential we have so I'm really excited about what we can produce in the next few years and I want to be a part of it.
"I'm really close to my family and friends (in Melbourne) but I love this club and I'm really excited that I get to stay and see what we can achieve."
The versatile 47-gamer, selected by Port with pick 14 at the 2019 national draft, is in the midst of a breakout season.
"Miles is an important and highly valued member of our team," Port's list manager Jason Cripps said.
"He has a unique skill set that allows him to influence games in multiple roles.
"Miles is an extremely determined and driven player who is starting to see the benefits of his hard work."
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