The 20-year-old Aston Villa midfielder was born in Solihull but represented the Republic of Ireland from under-15 to under-21 level.
He decided in September he wanted to represent England at senior level and has now finally been given clearance.
A FIFA spokesperson said: " The Single Judge decided to accept the request of The Football Association and the player Jack Grealish based on art
8 par
1 in conjunction with art
5 par
3 of the Regulations Governing the Application of the FIFA Statutes."
Article eight states that: "I f a player has more than one nationality, or if a player acquires a new nationality, or if a player is eligible to play for several representative teams due to nationality, he may, only once, request to change the Association for which he is eligible to play international matches to the Association of another c ountry of which he holds nationality."
That is conditional on the player not having represented his former country in a competitive senior match
Grealish meets those criteria, but he appears a much less likely England international than was the case when he made his decision in September
Despite Villa's dreadful season, Grealish has found himself on the sidelines
He has not appeared in the Premier League for more than two months and his last appearance in any competition for Villa was in the 4-0 FA Cup loss to Manchester City on January 30
Source : PA
Source: PA