The veteran Australian, whose contract was due to expire at the end of the season, has left with immediate effect.
It was always likely Rovers would move in a different direction for 2020 regardless but they have moved early given their current position of second-bottom in Super League.
Having been relegated in 2016, the East Yorkshire club simply can not risk the same fate again.
Rovers are just two points clear of bottom-placed London Broncos after winning only five of their 16 matches so far.
They were also knocked out of the Challenge Cup by Warrington Wolves last Friday when, afterwards, Sheens looked like a man who knew his time was up.
A club statement last night read: “Hull Kingston Rovers can confirm that Tim Sheens has left his position as head coach with immediate effect.
“A recent run of six defeats in seven league games during the current campaign, which leaves the club sat next to the bottom of the league, and an exit from the Coral Challenge Cup at the weekend, has prompted a change.”
Rovers have not indicated whether a new appointment will be in place for Sunday’s crucial Super League game when they host champions Wigan Warriors.
York City Knights’ highly-regarded James Ford, 36, has been widely tipped to take over although former Robins coach Justin Morgan and recently sacked Leeds Rhinos coach Dave Furner have also been linked with the post.
Assistant coaches James Webster and David Hodgson are set to take training today to continue preparations.
Reports broke on Monday that the club had sacked Sheens.
However, the 68-year-old – who coached Australia to victory in the 2013 World Cup final – saw a planned meeting postponed and he took training on Tuesday.
Rovers have already made off-field changes with John Bastian having moved from Bradford Bulls to become head of youth and stand-off Danny McGuire set to take charge of recruitment at the end of the season.
After Wigan, they host Warrington again before a vital trip to London on Thursday June 20.
The announcement was eventually made last night but some people will still see the parting of ways as a panic decision.
The experienced Sheens, renowned as one of the sport’s greatest coaches, has spent two-and-a-half seasons at KCOM Craven Park, lifting the club from the Championship back up to the Super League in his first year.
They finished tenth last term and had to fight for their place in the Qualifiers and they have found it difficult again this term.
That said, the club has been hamstrung by a wretched injury list and they have still been competitive in the majority of contests, offering hope they would improve with players now returning to fitness.