Mick Potter has opted not to take up the offer of a new contract with Bradford and will instead return to Australia.
The 48-year-old has been working without pay at the Bulls since being made redundant by the administrators on July 2 during a time when it appeared the Super League club could go out of business.
But while the future now looks much brighter at Odsal Stadium under the partnership of Omar Khan and Gerry Sutcliffe, they will have to find a fresh face to lead the team forward.
Potter, who joined the Bulls on a two-year deal after leaving St Helens at the end of the 2010 campaign, has already recommended his assistant Francis Cummins as his successor.
"I was always going to return to Australia and I feel that now is the right time for me to go," the former St George full-back, who has spent seven years in Super League, said.
"I have enjoyed my time at the Bulls and the supporters and people at the club are second to none.
"I feel, too, that despite circumstances out of our control the team, through the rugby league we played, showed a lot of character in the midst of terrible adversity.
"Omar Khan and Gerry Sutcliffe have come in and rescued the club and were very keen for me to stay for a longer tenure and I made it clear to them that my decision has nothing to do with their purchase of the club.
"It has been the things that have happened over the previous five months that have caused my decision.
"I will be watching Bradford Bulls with a lot of interest from Australia and it goes without saying that I wish them every success in the future."
Khan, sole director of the new club OK Bulls Ltd, and honorary chairman Sutcliffe, a former Sports Minister, saw their takeover ratified by the Rugby Football League this week.
They are still waiting to find out whether the team will be allowed to stay in Super League but have confirmed that they would have retained the services of Potter.
In a statement, they said: "We are sorry Mick has chosen to leave because we wanted him to stay longer with us after the tremendous job he has done in difficult circumstances.
"He leaves with the best wishes of everyone at the club and we wish him well in the future.
"We hope to be able to announce a new coach early next week."
Potter initially left Bradford during their financial crisis but opted to return after speaking to the players. Had it not been for a deduction of six points due to the club's off-field problems, the Bulls would have finished sixth instead of ninth and qualified for the play-offs.
He was named Super League Coach of the Year after guiding the Catalans to a third-place finish in 2008, a year after they had reached the Challenge Cup final, while he steered St Helens to the Grand Final in each of his two seasons at Knowsley Road.