Radio Tonga reports the commissioning was confirmed by a spokesperson for the Ministry of Infrastructure.
The TOP$25 million (US$11.4 million) project commenced in November 2015 and was completed in May this year by the Shanghai Construction Group.
The building was handed over to the Government of Tonga in June.
St George Government Building will accommodate offices of the Prime Minister, Ministry of Foreign Affairs and the Ministry of Finance and National Planning.
Photo file Kaniva News. Caption: Government ministers inspecting the new St George Government Building during the handover in June.