Footage was shared online last month by anti-hunt group Hertfordshire Hunt Saboteurs who said it showed members of the Cottesmore Hunt in Leicestershire.
At the time Mowbray Education Trust said Sarah Moulds had been suspended during a formal investigation and the RSPCA was also investigating.
The trust has now said the teacher has been dismissed.
Hertfordshire Hunt Saboteurs said the video was filmed near Sewstern in Leicestershire.
It was viewed more than two million times and condemned on social media by celebrities such as Judy Murray, Russell Tovey and John Bishop – who described it as “inexcusable”.
Paul Maddox, chief operating officer of the Mowbray Education Trust, said in a statement: “I can confirm that Sarah Moulds’ employment with the trust has been terminated.
“As a trust we are committed to ensuring the best standard of education for all of our young people and we look forward to continuing this throughout the 2021/22 academic year and beyond.”
Ms Moulds was also removed from a volunteering role she carried out for the Pony Club, which said of the video: “We wholeheartedly condemn this behaviour”.
The Cottesmore Hunt also said they “strongly disapprove of any such actions” and would “deal with it in an appropriate manner”