Former Samoa international Sene-Lefao helped Castleford reach both the Super League Grand Final (2017) and the Challenge Cup final (2021).
He said: “There are not many words that I can say that would show my appreciation for the club itself and what I’ve achieved over here.
“Every moment is special and there is definitely pride in the jersey that I wear every week. That is something I’m going to miss.
“It is sad to say that the time is up but, when one door closes, another door opens and it’s another opportunity for me and I’m excited for that.
“But our season isn’t finished. I’m looking forward to the next couple of games.
“From the first training session pretty much in the snow, it opened my eyes up with how things were going to be, the boys were awesome, very welcoming.
“It’s such a lovely feeling to know that I’ve played here for five years and to achieve the things that I have done here – I’m grateful.”
Castleford coach Daryl Powell said: “Jesse is such a bundle of energy – the fans love him because of who he is and the way he goes about things.
“He’s a very religious man, I ask him to say a prayer for us every now and then depending on what’s happening.
“He has been a quality player for us. 2017 was a massive year for him, I think he was unbelievable that year and he’s consistently been in our team as a back-rower since.”
Sene-Lefao made 44 NRL appearances for Manly Sea Eagles and Cronulla Sharks ahead of his move to Castleford in 2017. He won two caps for Samoa on the international stage in 2014.