The Spaniard, they said, used words that “made reference to race and/or colour and/or ethnic origin”.
The minimum suspension for a player found guilty of an aggravated breach of the FA’s discrimination rules is six matches, with punishment increased depending on additional aggravating factors.
The length of the ban matches that of the ban handed out to Luis Suarez when he played for Liverpool, having been found guilty of racially abusing Manchester United defender Patrice Evra back in 2011.
The Uruguayan, now at Barcelona, was handed a £40,000 fine in addition.
Sheffield Wednesday forward Fernando Foriestieri was handed a six-match ban and fined £25,000 last year after an independent regulatory commission found him guilty of using racist language in a pre-season friendly towards Mansfield Town defender Krystian Pearce the previous year.
In their statement on Casilla’s ban, the FA said: “Kiko Casilla has been suspended for eight matches with immediate effect, fined £60,000 and must attend face-to-face education after a breach of FA Rule E3(2) was found proven by an independent Regulatory Commission.