Wests Tigers chair Marina Go said the decision was not an easy one for the club to make.
"On behalf of everyone at Wests Tigers I'd like to thank Jason for his commitment and contribution to the club during his time as head coach," Go said.
"Jason has overseen significant change within the club over the past two seasons and we thank him for his efforts.
"Our position has always been to make sure that the head club's contract is tied to performance and that hasn't changed.
"We are committed to building a side that will be in a position to win NRL premierships and believe that this decision is the correct one for the future of the club.
"This is a challenging time for the club and Jason and we ask that we are given time to work through this process with Jason."
Current Wests Tigers assistant coach Andrew Webster will take on the role of interim head coach.
Webster returned to Wests Tigers this year after spending two seasons as an assistant coach at the New Zealand Warriors.
Picture: West Tigers Media