A Premier League managers arbitration tribunal upheld his claim West Ham were wrong to sell Anton Ferdinand and George McCartney to Sunderland against his wishes in September 2008.
Curbishley, 51, who resigned as a result of those transfers, is now in line for what is likely to be substantial compensation, which will be assessed by the tribunal.
Curbishley said in a statement on the League Managers Association website that he was "obviously delighted with the result".
He added: "I very much enjoyed my time at West Ham and never wanted to leave, but on joining the club I insisted that my contract contained a clause confirming that I would have final say on the selection of players to be transferred to and from the club.
"The club completely ignored my contract when selling Anton Ferdinand and, when George McCartney was then sold, the club having given me assurances that no players would be leaving the club after the sale of Anton Ferdinand, I had no alternative but to resign.
"My authority and integrity were undermined and my position was made untenable. I now wish to put this entire matter behind me."
Since leaving West Ham, Curbishley has worked as a TV pundit but has been linked with a number of high profile coaching positions.
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