The Championship club confirmed this afternoon that the former Huddersfield Giants chief would depart with immediate effect.
Featherstone say they told Sharp - who was appointed in July 2015 - this morning that his deal would not be extended into 2018.
It is a surprise as the 50-year-old had taken the part-time club into the Middle Eights against the odds last term and repeated the feat this time around, too.
However, the ex-Great Britain assistant will not take them into battle against the likes of Super League sides Warrington Wolves and Catalans Dragons.
Third-placed Featherstone would have kept hopes of a top-two finish alive if they had beaten Halifax yesterday but they lost 28-8 at home to their derby rivals.
Their final regular game is in Toulouse on Saturday but Sharp, assistant coach Danny Evans and head of strength and conditioning Billy Mallinson have all left immediately with the club saying a new head coach for 2018 will be announced tomorrow.
Rovers chairman Mark Campbell said: “We would like to take this opportunity to thank Jon for his efforts over the past couple of years.
“A decision to bring in a new head coach for 2018 has been taken and we feel leaving Jon in charge for the Qualifiers, only for him to depart in October, would make little sense.
“He leaves with our best wishes and we are now looking forward to seeing how our Super 8s campaign unfolds. We are aiming high and expect to leave a mark this time around.”
Sharp said: “It is with pride I look back at the successes we achieved, with highlights being the 2015 Championship Shield win over London and us becoming the first part-time team to achieve back-to-back top-four finishes - and a Challenge Cup quarter-final game.
“I want to thank the fans who have been amazing. To my staff, I thank them for their support and loyalty and to the players, who have been a pleasure to coach and a joy to work with.”