The singer was due to perform at the Sydney Opera House as part of her 'Number Ones: Up Close and Personal' tour, but the date has been axed on doctor's orders.
"Doctors have ordered Miss Jackson to undertake vocal rest for the next two days so she can complete the third and final show of her Australian tour this Tuesday night at the Sydney Opera House," a statement on Jackson's official website said.
"Unfortunately, there will not be a replacement concert scheduled, so all patrons will receive a full refund at the Sydney Opera House box office tonight or from the point of purchase."
Jackson previously postponed three shows in Melbourne to attend the wrongful death trial of her brother Michael's physician Dr Conrad Murray.
"When I planned these shows, the [trial] schedule in California was completely different. After talking with my family last night, I decided we must be together right now... This saddens me in so many ways," she said in a statement.
She also refused to play at the recent Michael Jackson tribute concert in Cardiff as it coincided with the Dr Murray trial.
Watch Janet Jackson's video for 'All For You' below: