The new deal means the 23-year-old backrower will remain with the club until at least the end of the 2021 season.
“I’m stoked with the situation and how it all panned out,” Yeo said.
“The club has shown tremendous faith in me and I’m looking forward to trying to repay that faith on the field with my performances.
“I think the last two years have been successful, especially given the age of our playing group, and I’m very confident with where this team is heading.
“I’m really excited to be here. It’s where I call home now.”
Originally hailing from Dubbo, Yeo tasted premiership success as he progressed through the grades at Panthers.
He was a member of the club’s premiership-winning NYC side in 2013 and backed up with victory in the NSW Cup Grand Final in 2014.
Yeo made his NRL debut that same year and has gone on to play 82 games and score 11 tries for Panthers.
“Isaah is an outstanding young man,” Panthers Executive General Manager Phil Gould AM said.
“He has come through the Panthers development system and now established himself as a mainstay in our NRL team.
“Isaah already displays tremendous leadership qualities and we are delighted he has committed his long-term future to our club.
“I have no doubts he will be a representative player in the years to come.”
Penrith Panthers 2019 Player Movements
|2019 Gains: None|
|2019 Losses: Tyrone Peachey (Gold Coast Titans)|
|Re-Signed: Dylan Edwards (2020), Tyrone May (2020), Isaah Yeo (2021)|
|Off Contract 2018: Oliver Clark, Kaide Ellis, Jack Hetherington, Adam Keighran, Jarome Luai, Nick Lui-Toso, Soni Luke, Josh Mansour, Chad O'Donnell, Joey Peato, Tyrone Phillips, Corey Waddell, Jayden Walker, Peter Wallace|