The rock was brought from Birdwood Station, in the Ahuriri Valley, after a search for one that was big enough and had a flat surface on which plaques could be mounted commemorating Omarama district war casualties.
It has been placed outside the police station in Omarama and brass plaques will be made by Gillies Metaltech in Oamaru.
Upper Waitaki RSA president Mike Blackstock said one of the difficulties was finding a piece of rock with a big enough flat surface.
Omarama has a war memorial hall which has memorial plaques inside, but a stand-alone war memorial would give freer public access.
A flag pole would be erected next to the rock and it was hoped the new memorial would be completed by Anzac Day this year so a service could be reintroduced to the town.
The last Anzac Day service was in the 1970s.
The new memorial will not replace the memorial hall as the town's war memorial, but rather be an addition.
