Huntley was born in Wiston, West Sussex, the son of Karen and Graham Huntley. He was educated at Windlesham House School in Pulborough, Sussex, at Leighton Park School in Berkshire and at Our Lady of Sion convent in Worthing.
His early acting career included roles in 28 Days Later and True Blue. He later appeared in Snow White and the Huntsman and Dracula Untold. On TV, he played Luke McAllister from 1993 to 1995 in the British soap opera Emmerdale; he also played Will Curtis in Holby City for the 2004-05 season, and Michael Dillon in the football drama Dream Team. He broke his nose filming a fight scene with his co-star Luke Mably. Since 2010 he has also been seen in modeling campaigns for several large brands.
In 2005, he appeared in "The Chronicles of Narnia: the Lion, the Witch, and the Wardrobe" playing the older version of High King Peter (Pevensie) - the younger version of which was played by William Moseley.