McCann has signed a one-year rolling deal at the Championship, just shy of a year since he was appointed at Rovers.
Speaking about his move, McCann said: “I am delighted to be here and I’m looking forward to the challenge ahead.
“I am a very ambitious person and I always have been.
“To be in the Championship is the next step for me, and I’m pleased to be taking that step with a great club like Hull City.
“The KCOM Stadium is an impressive place, the training ground is excellent and there is a strong squad of players here.
“Hopefully we can have good times together and a successful season.”
Hull turned their attentions to McCann as the man to replace Nigel Adkins earlier this week.
By Thursday they had made an official request to Rovers in order to speak with the Northern Irishman with an agreement following swiftly after.
Tigers vice chairman Ehab Allam said: “Grant has been a standout candidate with a playing style and philosophy aligned to that of the Club.
“With a great team of existing staff in their support and of the squad too, I hope for an exciting season ahead.”
Assistant manager Cliff Byrne will follow McCann to Hull.