On New Year's Day, 1901, the inauguration of the Commonwealth of Australia was conducted at a formal ceremony in Centennial Park in Sydney, following a lengthy procession through the extravagantly decorated city streets. Members of this procession included a military contingent from South Australia, and the estimated 250,000 people watching the parade included many leading citizens from this state.

At the inauguration ceremony, Edwin Blackmore, Clerk of the South Australian Parliaments, read the principal document which instituted the new nation, the Proclamation of the Commonwealth.

When the Commonwealth of Australia came into being, the colonies became states. Lord Tennyson was sworn in as South Australia's Governor at the Adelaide Town Hall with due ceremony. Additional Commonwealth celebrations included church parades, and military sports at the Jubilee Oval, followed by a 'Continental' concert in the evening with a 'grand parade of illuminated bicycles'. Local celebrations took place at several country towns, such as Hawker, Mount Gambier and Yorketown.