He began his career as a child model at age 7 after meeting Ralph Lauren in a New York City store. He appeared in his first commercial when he was six.
Company's, a British women's magazine, voted him the 35th most eligible bachelor in 2009.
He dated his I Am Number Four co-star, Dianna Agron, from 2010 to 2011 and was engaged to Riley Keough in 2012. He then dated model Marloes Horst from 2014 to 2016. In 2018, he dated Gabriela Giovanardi. He got engaged to Toni Garrn in 2019 and the couple got married in 2020. In July 2021, Garrn and Pettyfer welcomed a child together. He has a younger half-brother named James.
He appeared alongside Channing Tatum in the 2012 film Magic Mike.