Turkish businessman Acun Ilicali completed a £20 million takeover of Hull last week with McCann subsequently steering his side 10 points clear of the Championship relegation zone with shock wins over promotion candidates Blackburn Rovers and Bournemouth without conceding a goal.
McCann led the Tigers to the League One title last season, pipping Posh to top spot, but that has not saved him from a sacking which will be seen as harsh within football. His assistant Cliff Byrne has also left the club.
Former Georgian international player Shota Arveladze, who last managed a team in Uzbekistan in 2020, is the favourite to replace McCann.
Ilıcalı said: “Grant has done an excellent job for this football club in difficult circumstances, most specifically during the takeover process, and for that I offer my sincere thanks.
“These matters are never easy and are more often than not protracted. During the process, Grant has always remained professional and fully focused on the team, and will forever be a friend of the Tigers. I’m sure Grant will be successful in whatever his next challenge is.
“However, now is the time for change and for me to start to build, in what I believe will be an incredibly exciting time for the club. I have a philosophy and a belief that our project should start as we mean to carry on and that involves having my team in place. I understand the timing may look odd, after two good wins, but I wouldn’t be fair or honest if I merely waited for a defeat to change manager. “That benefits nobody. I will continue to be transparent with you, our fans.
“Our new head coach will be announced very shortly.”