Feild was born in Boulder, Colorado, but moved to London as a baby. He is the son of British mystic and author Reshad Feild. He has dual British and American citizenship.

During his school years at Fine Arts College, Hampstead, he became heavily involved in acting, and entered the Webber Douglas Academy of Dramatic Art at the age of seventeen.

Since graduating from drama school in 1999, he has appeared in several films as well as gaining a variety of television roles. He can be seen playing the role of Simon Doyle in the television series Poirot, and has also appeared in Northanger Abbey alongside Felicity Jones as well as the televised version of The Ruby in the Smoke alongside Billie Piper.

In 2008 he made his West End debut in Ring Round the Moon.