"Initially, his (Toutai Kefus) condition was described as critical, but it is believed that he will survive," Tony Fleming from the police told ABC News.
According to local media, the family was awakened at 03:00 by robbers entering the home.
In addition to Kefu, his wife and two children (18 and 21 years old) were seriously injured and are being cared for in hospital.
They must have been attacked with an ax, a knife and a machete.
Two suspects, who are said to be boys in their 15s, have been arrested.
47-year-old Kefu played in Australia's rugby national team for seven years. In 2016–2019, he was Tonga's national team coach, a job he got back earlier this year.