The FEI had asked to stand down earlier this month after the International Olympic Committee (IOC) expressed concerns about judging standards at the Beijing Games in August.
The official refused at first but her offer to resign today was accepted, the FEI said in a statement.
In today's statement the FEI said: "Considering the present situation, the chairman of the FEI dressage committee decided to present her resignation, which has been accepted by the FEI."
She had been the chair of the committee for nearly eight years.
The announcement came as FEI president Princess Haya of Jordan, an increasingly influential member of the IOC, addressed officials from around 80 national federations at their annual assembly in Buenos Aires.
She told the assembly that "no one committee is bigger than the sport."
The Princess said the FEI had endured "a bumpy ride" during two years of modernisation since she was elected.
She said the IOC had concerns about rider safety in eventing competitions and the quality of dressage judging.
The FEI had long-standing frustrations with the dressage committee for being difficult to deal with and asked the six-member panel to resign.