The New Zealander, 28, initially joined the Tigers ahead of the 2020 season from Betfred Championship side Toulouse Olympique.
With his physical approach, he has made a number of impressive performances without yet nailing down a regular spot.
He hopes to do that in 2022 and 2023 having pledged his future to the West Yorkshire club.
“I’m very excited,” said Hepi, who briefly played for Hull KR earlier in his career.
“I’ve enjoyed my time at Castleford already and I have learned a lot from the boys that have been here with me for those two years.
“I am looking forward to seeing what the future holds.
“I’ve got my house here and have some good friends in the community and we are a pretty tight-knit group at Cas.
“I am really excited to crack on for another two years and really start pushing to make a name for myself.”
He has made almost 20 Super League appearances with Castleford but is keen to do more.
“I am very eager and working really hard,” added Hepi, who praised the influence of departing head coach Daryl Powell on him.
“Next year I am going to be relentless in going for that starting spot.
“I have been here two years now and have set a solid foundation, so for me it is time to crack on.”
With Australian prop Grant Millington have now retired, Hepi has scope to do that under new head coach Lee Radford who has already brought in new signings like Jake Mamo, Kenny Edwards, and Alex Sutcliffe.
Hepi added: “There are good new faces coming in, high-calibre players.
“I know Kenny Edwards; I have known him when we were both in France and both being Kiwis.
“He is a good fella and with Radders coming in everyone is pretty excited to have him on board.
“He is going to be a fresh face around here which will bring new coaching ideas and a new attitude of coaching.
“I think it is an exciting time for the club - and Castleford as a whole.”
Radford said: “Tyla plays with a really good energy.
“I like what he does and what he brings to the team.
“I actually played with his dad which is a sign of my age!
“He’s a real honest working front-rower and one I am really looking forward to coaching.”