The decision to base the vessel in the Victorian capital is the result of unprecedented demand, according to Carnival Cruise Line's president Christine Duffy.
The cruise company is anticipating a record season, with a total of 16 sailings planned during 2018-2019.
The move comes as Port Sydney struggles to cope with the huge number of visiting cruise ships during the summer season.
Carnival is planning a US$57-million upgrade for Legend in May 2018, which will refurbish the eateries, bars and attractions onboard.
Carnival Legend is now off to New Caledonia, with visits to Noumea, Mare, Lifou Isle and Isle of Pines. Melbourne will homeport the ship until March, and it returns for 2018-2019 season in November.