The first cancellations were announced in March as a 30-day operational pause but were then extended three times in light of the pandemic.
Guests can choose between refunds, vouchers or moving the booking to a later date.
The group is currently completing the repatriation of nearly 29,000 crew members to more than 100 nations who serve its fleet of 27 ships.
“We have watched with great interest as commerce, travel and personal activities have begun to start back up, and once we do resume service, we will take all necessary steps to ensure the health and safety of our guests, crew and the communities we bring our ships to in order to maintain public confidence in our business,” said Carnival Cruise Line President Christine Duffy.
Shares dropped 8% to 1,144.9p on Monday before close.