The 2,996-passenger ship will continue sailing for Cunard until the end of its 2028/29 World Voyage before undergoing an "extensive reimagining" and be renamed before entering service for its sister brand in May 2029.
Carnival UK, P&O Cruises and Cunard President Paul Ludlow revealed the renamed Queen Anne ship will be the maiden vessel in a new class of ship for P&O Cruises.
In a related move, Arcadia, a P&O Cruises ship which entered service in 2005, will transfer across to Holland America Line in May 2029.