Eden, 27, began his career with Tigers, making his Super League debut in 2011, before moving to Huddersfield Giants.
He also spent time with Hull KR and Salford Red Devils before moving to Australia at the end of 2014 to join NRL side Brisbane Broncos.
Eden returned to Tigers ahead of last season and finished 2017 with 41 tries in all competitions, earning him a place in the Super League Dream Team.
He has been struggling with injury this term but said: “Last year I was really enjoying my rugby and I feel like I slotted straight back into the Castleford way of playing.
“I have really enjoyed my time here since I’ve been back and I’m ecstatic to have extended my contract.
“I’ve not had the best of luck so far this season, with a hamstring injury keeping me out for a few weeks, but I’m excited to get back out there with the boys.”
Coach Daryl Powell described Eden’s new deal as “great news” for Tigers.
He said: “He had a fantastic first season with the club and I have no doubt this season it will be the same when he gets consistent game time under his belt.
“He is a natural try scorer and is a lightning quick player who can play both on the wing and at full-back.
“I’m looking forward to working with him and seeing him develop further in the coming years.”
Tigers’ director of rugby Jon Wells added: “You shouldn’t reduce an individual’s career to plain statistics, but in the case of Greg Eden it is worth having a look because his appearance to tries ratio makes impressive reading - 116 first grade career appearances and 82 tries, including 41 tries in 36 matches for Cas last season which is a phenomenal strike rate.
“Now seen as a proven outside-back of the highest quality, he provides both points and backline options for Castleford and we are very pleased he has decided to commit his future to the Tigers.”