It is said that P&O "invented" cruising. In the 1880s the Orient Line and the North of Scotland company, both later to be taken over by P&O, pioneered modern-style cruises, and in 1904 P&O offered its first cruise holiday programme, a first class only cruise with shore excursions arranged by Thomas Cook. The tour used the 23-year-old liner Rome, renaming her 'Vectis' in her new role as a "cruising yacht."

Between the wars cruising became more popular, often using the newest ships in the fleet rather than the oldest. Tourist class cruises began in the early 1930s followed by Pacific cruises from Australia a few years later.

With no rigid mail contracts after 1945, cruising became still more important to the shipping industry. P&O Cruises last ship built for scheduled line voyages, Canberra, was delivered in 1961 but in little more than a decade jet airlines had taken over the company's traditional passenger trades while the container ship packed up liner cargoes.

Forced to concentrate on the leisure side of sea travel, P&O Cruises abolished passenger classes, acquired Los Angeles-based Princess Cruises in 1974, and Sitmar Cruises in 1988. Sitmar cruises was then merged with Princess Cruises. Since the beginning of the 1990s, Princess Cruises has embarked on a policy of growth through building new ships, bought and later built purpose-designed cruise ships and became one of the largest cruise operators in the world.