Frankel has become the first ever horse to retain the title of Cartier Horse of the Year.
The four-year-old colt extended his unbeaten record to 14 races with victory in the QIPCO Champion Stakes at Ascot last month.
Trainer Sir Henry Cecil said: "All of us at Warren Place are thrilled that Frankel's achievements this year have been recognised with him winning this most prestigious award for the second time running.
"Frankel with his brilliance has been a great ambassador for British Racing and has captured the hearts of so many people, some of whom have never been racing in their lives.
"Thank you Frankel and to everyone that has voted for him."
Frankel, who was retired to stud following his Ascot win, earned almost £3m in prize money during his career.