The superstar racemare polled 236 of the 283 votes cast to prevail over Triple Crown winner Contrail and his filly counterpart Daring Tact to win the prestigious prize for the second time. It is the third year running that the top award has gone to a female horse.
Sakae Kuneida, who trained Almond Eye for Silk Racing, said: "I am honoured to receive this award."
Almond Eye signed off an outstanding career with an epic victory under regular jockey Christophe Lemaire in the 40th running of the Japan Cup, the country's joint-richest race alongside the Arima Kinen, in November.
In what was billed as the 'Race of the Decade' she scored a decisive victory over the three-year-olds Contrail and Daring Tact, who filled second and third places.
She is currently rated world #1 on the Thoroughbred Racing Commentary's global rankings.
Almond Eye was also named best older filly and mare while Contrail received the consolation of the best three-year-old colt title after becoming the first male Triple Crown winner to miss out on the top prize since the awards were established in 1954.
Contrail, who remains in training, is expected to have his first start of 2021 in the G1 Osaka Hai at Hanshin on April 4.