God has some pretty big shoes to fill but two people were chosen to fill that role in Fruits Basket: The Final Season depending on what language you choose to watch the anime in!
It was announced that the voice of God will be played by Hiroshi Kamiya in Japanese and Matt Mercer in the English Dub.
Kamiya previously held roles for Levi Ackermann in Shingeki no Kyojin, Akashi Seijuro in Kuroko no Basuke, and Yato in Noragami while Matt Mercer previously lent his voice to characters such as Levi Ackermann in Shingeki no Kyojin, Jotaro Kujo in JoJo’s Bizarre Adventure, and Trafalgar Law in One Piece.
Source: Funimation