The announcement comes days after FIFA ratified Rice's switch of international allegiance from the Republic of Ireland to England.
The 20-year-old played for the Republic of Ireland's youth teams before representing them three times at senior level.
But those three appearances all came in friendly internationals, allowing West Ham academy graduate Rice to switch to England.
A statement from the FAI read: "The award was voted for by members of the SSE Airtricity Soccer Writers' Association of Ireland.
"At the time of the vote, Declan Rice was an Ireland international and qualified for the Young Player category in a year that saw him win three senior caps, all in three International Friendly games.
"Declan Rice has since opted to switch his allegiance to England. The FAI has completed his international transfer via the FIFA protocols and wishes him well in the future."