Tua Tagovailoa is officially a Miami Dolphin after the team announced on Tuesday the former Alabama star quarterback has signed his rookie contract.

Under the NFL's rookie scale, Tagovailoa will receive $30.275million guaranteed over four years. The deal contains a signing bonus of nearly $19.6million and contains a fifth-year option for 2024.

Miami selected Tagovailoa, the 2018 Heisman Trophy runner-up, with the fifth overall pick in last month's NFL draft in the hope of landing the franchise quarterback the team has been seeking since Dan Marino's retirement in 1999.

The Dolphins have not had a quarterback make the Pro Bowl since Marino in 1995 and are the only team to have had a different QB start 10 or more games in each of the last three seasons.

They confirmed the done deal on their official website, stating: "The Miami Dolphins today announced they have signed the following four draft picks: first-round quarterback Tua Tagovailoa, second-round defensive tackle Raekwon Davis, fifth-round defensive end Curtis Weaver and sixth-round long snapper Blake Ferguson."

Tagovailoa's college career was cut short when he dislocated his right hip in mid-November of his junior season at Alabama, but he was cleared to resume football activities in March and held a virtual pro day for NFL teams on April 9.

The 22-year-old led the FBS rankings in 2019 with a 206.9 passer rating while completing 71.4 per cent of his throws with 33 touchdown passes and only three interceptions. As a sophomore the previous season, Tagovailoa threw for 3,966 yards and 43 touchdowns in 15 games and finished second to 2019 number one overall pick Kyler Murray in voting for the Heisman Trophy.

Miami re-signed veteran Ryan Fitzpatrick in March, giving the Dolphins insurance if Tagovailoa is not deemed ready to start the team's scheduled September 13 opener at New England.