Born in London, England and son of a British World War I hero, Lawford had spent most of his childhood in Paris, France and began his acting career at a very young age. His parents were not married when their son was born. As a result of the scandal, The Lawfords fled to America.

As a young child, the young Peter injured his arm by in his own words, "attempt to run through a glass door." Lawford's arm was badly injured however, the doctors could save it. The injury was so bad, it was slightly deformed and bothered him throughout life. But such was his luck, the injury kept him off the draft for World War II, which became the biggest boon of his acting career.

When Lawford was signed to MGM, his mother approached studio head, Louis B. Mayer, to pay her a salary as her son's personal assistant. However, Mayer declined. She then claimed that her son was "homosexual" and needed to be "supervised". This damaged the relationship between her and her son.

Lawford starred in his first major movie called A Yank at Eton (1942) , co-starring Mickey Rooney, Ian Hunter and Freddie Bartholomew. His performance was widely praised. During this time, Lawford started to get more leads when major MGM star Clark Gable was drafted into the war. Later, it was Good News (1947), co-starring June Allyson that became Lawford's greatest claim to fame.

Probably Lawford's most controversial affair, amongst many, was with African-American actress Dorothy Dandridge. It was rumored that both Lawford and Dandridge were planning to get married but canceled fearing it would jeopardize their careers.

Besides his successful career and being a socialite, Lawford was also part of the Rat Pack, with Dean Martin, Frank Sinatra, Joey Bishop and Sammy Davis Jr. .