The deal, which was finalized Monday, keeps Sorensen under contract through the 2020-21 season.
The 26-year-old Sorensen is in his third season with the Sharks. He has career highs with eight goals, seven assists and 47 games played.
Sorensen originally signed with San Jose in May 2016 after playing professionally in Sweden. He played 41 games in the NHL his first two years with six goals and five assists.