A shining light for the expansion team, Marshall-King has been a highlight for the Dolphins to begin the 2023 season.
After joining from the Bulldogs where he won the 2022 Player of the Year, he was easily the best player in the Dolphins' first two games against the Roosters and Raiders.
At the Bulldogs, he played 99 games across five seasons and also had a stint at the Wests Tigers in 2017.
The extension allows Wayne Bennett to lockdown his spine for the future. It also means the club will only have five players off-contract at the end of the season; JJ Collins, Kurt Donoghoe, Poasa Faamausili, Oliver Gildart and Tesi Niu.
"It has been a great move for my family and we have enjoyed ourselves immensely up here," said Marshall-King on the Dolphins website.
"I want to thank the Dolphins' fans and the local community for how they have welcomed us."
"I am really excited about what is ahead for the future of the Dolphins and I want to be part of it."
Terry Reader, chief executive of the Dolphins' gave his input on the star hooker and praised his great start to the season.
"Jeremy has made an immediate impact at the Dolphins not only on the field, but off the field as well," Reader said.
"We are so pleased to extend his contract this early in his first year at the club and reward him for the great form he has showed so far."
"It means we have secured a world-class hooker for the next three years and this is a great boost as we continue to build our roster for the future."