The ceremonies were part of the commemorations of the World War 1 battle of Chunuk Bair, where more than 140 Otago soldiers died.
More than 80 people marched from the Portobello Bowling Club, in Sherwood St, to the Otago Peninsula Museum and Historical Society building in Harington Point Rd on Saturday afternoon.
During the later unveiling ceremony, the Last Post was played by a bugler, Portobello volunteer firefighter Kelven Gaskill.
Lcpl Geary, was a member of the Otago Mounted Rifles and the Maori Contingent, was the son of William and Mary Geary, of Portobello.
On behalf of the Geary family, Orma Blackler, of Portobello, unveiled the plaque, which is on an Anzac memorial stone in the museum's grounds.
Geary family members laid a wreath, lodge members lay sprigs of acacia by the plaque, and the Masonic Choir and members of the public sang The Maori Battalion.
Toni Gordon, of Dunedin, Lcpl Geary's great niece, spoke before the commemorative unveiling.
She later said the commemorative events had gone very well and recent associated research about John Geary had increased awareness within the Geary family about his life.
