The Dolphins have secured Selwyn Cobbo through the end of 2031 and extended forward Kulikefu Finefeuiaki for two additional seasons.
The announcements strengthen the club's roster ahead of its first NRL preliminary final, although salary-cap pressure remains a concern.
Cobbo joined on a one-year contract, extended it in April, and has since scored 18 tries in 19 matches.
The 24-year-old Queensland winger was previously on the outer at Brisbane but has flourished since moving to the Dolphins.
"Selwyn has made an immediate impact since joining the Dolphins, and what he has been able to produce in his first season at the club has been remarkable," CEO Terry Reader said.
Reader added, "He has quickly become an important part of the team, and to have a player of Selwyn's calibre committed to the club through until the end of 2031 is a great result."
Finefeuiaki had been due to become available to rival clubs, including the tax-free PNG Chiefs, on November 1 after the 2027 season.
The 22-year-old established himself as a key forward, earned his State of Origin debut, and will now remain in Brisbane beyond his existing deal.
Finefeuiaki debuted for North Queensland in 2023 before joining the Dolphins in 2025.
"We see Kuli as one of the cornerstones of the pack and are excited about what he can do for this club," Reader said.
Herbie Farnworth, Hamiso Tabuai-Fidow and Jack Bostock remain major retention issues, with all three currently facing free agency from November 1 next year.
The Dolphins have also retained Tom Gilbert, Kurt Donoghoe, Max Plath, Tevita Naufahu and Brad Schneider on longer-term deals.