The incumbent on the business was MRM Meteorite. The pitch process began in April.
Lida will begin strategic and creative work immediately. The agency is tasked with transforming the cruise companies’ direct-to-customer marketing as they try to adopt a more personal, customer-led approach.
Jeremy Tait, the P&O and Cunard insight director, said: "In an increasingly competitive market where personalisation is key, it is crucial to put our guests at the forefront of all that we do, from the moment of consideration to the time they return home and think about their next holiday."
The7stars picked up the £12 million P&O and Cunard media planning and buying account last year.
Carnival celebrated the 175th anniversary of Cunard this year. P&O was founded in 1837.