Carnival Corporation entered into a strategic agreement with Italian shipbuilder Fincantieri in March 2015 for five cruise ships to be delivered between 2019 and 2022.

Costa first announced on 6 May 2019 that the ship would initially spend her first month sailing in the Mediterranean and call at ports in Italy, Spain, and France.

Her original maiden voyage was scheduled for 1 October 2020, departing from Trieste and calling at Bari, Barcelona, and Marseille, before arriving in Savona.

[16] But in August 2019, Costa cancelled her maiden voyage and first month of sailings in favor of repositioning the vessel to Singapore immediately following her delivery, after which she would debut in the Chinese market on 20 October 2020.

[20] Then, in October, Costa further delayed the ship's debut in the Mediterranean with a new maiden voyage set for 28 February 2021,[11][21][22] which was later annulled by cancellations announced in January 2021.

[25][26][27] She then followed her summer debut season with her maiden circuit in the Persian Gulf, where she operated week-long voyages from Dubai between December 2021 and March 2022.

[41][42] The ship left the shipyard on 22 March and sailed to her new homeport of Long Beach, California, after which she was christened by her godfather, American actor Jonathan Bennett, on 24 April.

[43][44][45] Originally scheduled to sail her inaugural voyage on 2 May 2024,[46] Carnival Firenze commenced operations one week earlier, on 25 April, to the Mexican Riviera, a region to which she is deployed on a year-round basis.