Samuel George Claflin was born on 27 June 1986 in Ipswich, England as the third of four sons to Mark, a finance officer, and Sue Claflin, a classroom assistant. He has two older brothers, Benjamin and Daniel, and a younger brother, Joseph, who is also an actor.
As a child, Claflin had an interest in football. He played throughout his childhood until he broke his ankle, an injury that he felt would prevent him from ever playing professionally. After some persuasion from his parents and a teacher whom he'd made an impression on at his high school (Costessey High School in Norwich) during a play performance, he pursued acting. He was a member of the School of Excellence for Norwich City FC. In 2003, he took up Performing Arts at Norwich City College, before going on to attend the London Academy of Music and Dramatic Art, from which he graduated in 2009.
Claflin is best known for his roles in Pirates of the Caribbean: On Stranger Tides, United and Snow White and the Huntsman. He was also in the short BBC TV series White Heat, and starred in a new film in 2014.