Derby County chairman Mel Morris has become the club's sole owner after buying out the American ownership group for an undisclosed fee.
The Derby-born businessman took a 22% stake in the Rams in May 2014 and became chairman in May this year.
"I hope together we can help steer this club into a sustainable place in the Premier League," Morris said.
Morris first joined the Rams' board in 2006 and has become increasingly involved since returning as a director.
Derby narrowly missed out on promotion from the Championship when they lost the 2014 play-off final against Queens Park Rangers and fell just short of making the play-offs last term after a poor end-of-season run.
Former Real Madrid assistant Paul Clement was appointed as manager in the close season and Morris said "many of the key components were in place" to help the Rams return to the top flight.
But he said: "I am conscious that we must all commit our total support in pursuit of this goal, which I know is shared by all of us.
"I wish to pay tribute to the North American ownership group [North American Derby Partners LLP], who collectively provided the finance and leadership stability the club needed following the traumatic times which followed the 2007/8 season in the Premier League.
"They have been terrific to work with, and I am sure they will continue to follow the Rams well into the future."