P&O Cruises Australia has extended its pause in cruise operations into mid-September.
The line has cancelled all voyages scheduled to depart up to an on 17 September.
Its voluntary halt in operations had previously been due to expire on 31 July.
"The extended pause is being applied as the cruise industry continues to work with relevant government authorities to establish a pathway for the restart of cruising in Australia," said P&O.
Guests with affected bookings will be notified of their options directly or via their travel agent.
President Sture Myrmell said the move was designed to give guests enough notice to plan their holidays with "as much certainty as possible".
"We are supporting our industry association as it works with governments and public health authorities to develop a framework for the successful resumption of cruising," said Myrmell.
"We look forward to the day when a pathway is confirmed for cruising’s return so that we can welcome everyone back onboard. For now, we continue to assist our guests in every way we can in spite of the current uncertainty."