Pearson, who quit his role as Derby chairman to return to the KC Stadium, replaces Paul Duffen who quit as Hull chairman last week.
Pearson said: “I am delighted to be back at Hull City as chairman.
“Hull City is a club I know well and care passionately about.
“There are obviously significant challenges ahead but with real hard work from me and my staff, allied to the usual outstanding support of Hull City fans, I am sure we will take the club forward again.”
Pearson was in charge at Hill from 2001-07 and helped move the club to the Championship.
