Due to lack of new-building capacity, TUI Cruises started by acquiring the cruise ship Celebrity Galaxy, which was built by Meyer Werft and was owned by another RCCL subsidiary, Celebrity Cruises. She left the Celebrity fleet in 16 March 2009. After acquiring Celebrity Galaxy, the ship headed to Lloyd Werft shipyards in Bremerhaven, Germany. She arrived on 27 March 2009, and received a € 50 Million, 38-day conversion to upgrade her facilities to suit a German-speaking market. After the conversion, she was re-christened on 15 May 2009 in Hamburg, Germany bearing her new name, Mein Schiff (My Ship). TUI planned to build two 2,500-passenger, 100,000-GT cruise ships in 2011 and 2012.
On May 27, 2010, it was announced that another Century-class ship, Celebrity Mercury, would become the latest addition to TUI's fleet, renamed Mein Schiff 2. She entered service with TUI in February 2011 after its extensive refurbishment, with the addition of more verandas, an expanded wellness area and design elements which are found on Mein Schiff 1.
TUI and STX Finland announced a contract on 27 September 2011 to build a 97,000-GT vessel, which will be delivered in 2014. The vessel will be approximately 295 metres (968 ft) long and approximately 36 metres (118 ft) wide. The ship will have 1,250 staterooms, most of which will have balconies, with a capacity of 2,500 passengers and a crew of 1,000. The ship will include several restaurants, a theater, a spa and a nightclub. The contract included an option to build a second ship, dependened on the approval of TUI Cruises shareholders. Its was announced on November 5, 2012 that TUI ordered the second option for the ship sister to the Mein Schiff 3.