"I would like to thank the players, my coaching staff and, of course, the fans for their magnificent support and commitment during my time as manager and I wish them well for the future.
"I would also like to take this opportunity to thank the League Managers' Association and its advisors for their excellent support over recent months."
The deal means Brown, who had refused to rule out a return to the KC Stadium, is now able to seek employment elsewhere.
Brown took over as Hull caretaker manager in December 2006 with the Tigers 22nd in the Championship and was promptly offered the job on a full-time basis after inspiring a revival.
Hull won promotion to the Premier League for the first time in their history the following season after beating Bristol City in the play-off final.
The Tigers just managed to survive relegation in their debut season in the English top division but with the side languishing in the relegation zone the following March, Brown was put on gardening leave.
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