Patrick Joseph Kennedy, the son of Irish immigrants, was born in Boston on 14th January, 1858. His father, Patrick Kennedy, died of cholera ten months after he was born. His mother, Bridget Kennedy, who also had three daughters, found work as a clerk in a shop.

Kennedy attended the Roman Catholic school, Sisters of Notre Dame, before finding work in the East Boston Shipyards. In 1880 Kennedy borrowed money from his mother and sisters to purchase a run-down saloon in a poor area of Boston. Although he was himself a teetotaler, the business venture was a success and he was soon able to obtain a second saloon. In 1885 he started his own wine and spirit importation business, P.J. Kennedy and Company.

In 1887 Kennedy married Mary Augusta Hickey, the daughter of a prosperous businessman in the city. A member of the Democratic Party Kennedy was elected to the Massachusetts Senate in 1892.

Along with John Francis Fitzgerald, Kennedy became the most important political figure in Boston. In 1914 Kennedy's son, Joseph Patrick Kennedy, married Fitzgerald's daughter, Rose Fitzgerald: the parents of John Fitzgerald Kennedy, Robert Kennedy and Edward Kennedy. Patrick Joseph Kennedy died in 1929.