Terms were not disclosed, but it is worth up to $7.85 million with $3.2 million guaranteed, a source told ESPN's Adam Schefter.
Acquired in late July from the Chicago Bears for a conditional 2021 seventh-round pick, Shaheen has made the most of his fresh start in Miami. He has nestled in well in the Dolphins' three tight end rotation with Mike Gesicki and Durham Smythe, proving to be an asset as a blocking and receiving weapon.
Shaheen, a 2017 second-round pick, was entering the final year of his rookie deal and now has more long-term security. His first three years in Chicago were often mired with injuries.
Shaheen, 26, has a touchdown in each of his past two games and had a career-high 51 receiving yards in an Oct.18 win over the New York Jets.