Hamilton was born at Lister Hospital in Stevenage, England, He was named after American sprinter Carl Lewis. His mother, Carmen Larbalestier (now Carmen Lockhart) is British. His father's parents emigrated from Grenada to the United Kingdom in the 1950s.[9] Hamilton's parents separated when he was two. At first he lived with his mother. When Hamilton was twelve, he started living with his father, Anthony. Hamilton was raised Roman Catholic.
Hamilton's first taste of racing came at radio-controlled cars. His father bought him one in 1991, and Hamilton did well. Hamilton started kart racing when he was six. His father bought him his first go-kart as a Christmas present. His father said he would support his racing as long as he worked hard at school. To support his son Anthony had to take extra jobs, but he found enough time to attend all of Hamilton's races.