Holmes’ contract was set to expire at the end of this season but now his new deal will see him with the Tigers until at least the end of 2018.
The 23-year old has appeared in over 100 games for his hometown club and he has been a permanent fixture in the starting line-up, having joined the Tigers back in 2008.
In 2015, the second rower played in 28 games and scored five tries as he helped Castleford finish 5th in the Super League, and was part of the Tigers side to reach Wembley in the 2014 Challenge Cup Final.
“I’m really happy to have committed my future to my hometown club,” Holmes said.
“I wouldn’t want to leave a club like Cas. There’s something very special going on here right now and I’m excited to be part of it.
“I’ve been here since my academy days and it’s just home to me. This is all I have ever known and I’m so happy here.
“Losing Michael Shenton this early in the competition is a massive blow for us, but that’s why we have a 29 man deep squad. We have people here who can slot in and do the job for us.
“Obviously it is disappointing to lose our captain, but we’re still a strong team, and knowing Shenny he’ll still be heavily involved during his recovery.”
Tigers coach Daryl Powell credited Holmes’ continued development as one of many reasons for his contract extension.
“Oli Holmes is one of the toughest young players I have seen in my time as a coach,” Powell said.
“His defensive work is superb and I believe he will grow to be an outstanding leader at the Tigers. He has already shown his durability as a young player at the club and I believe if he continues to improve he will go on to play at the highest level.”