Conservative Sir Edward Heath served as prime minister from 1970 to 1974, while Labour’s Lord James Callaghan was Prime Minister from 1976 to 1979.
It was under Sir Edward’s premiership that Britain entered the European Economic Community in 1973.
Both men died in 2005, Sir Edward at the age of 89 and Lord Callaghan at the age of 92.
The announcement coincides with the 100th anniversary of Lord Callaghan’s birth.
The Dean of Westminster, the Very Rev Dr John Hall, said: “The men and women who have contributed most to our island story and our nation's international influence are memorialised in the Abbey, including most Prime Ministers of the 19th century and of the first half of the 20th century.
“And yet no Prime Minister since 1956 has a memorial in the Abbey. I am happy to announce that I have decided with the support of those closest to them to include amongst those remembered in the Abbey two Prime Ministers from the 1970s, each of whom gave dutiful service in their own time. Although [Lord Callaghan] and Edward Heath were on the opposite side of many political arguments, they were both of that remarkable generation that served in the Second World War and continued to devote their lives to the service of their nation and of the world. It is fitting that we should honour them.”