The species is endemic to the Poor Knights Islands of New Zealand.

[1] O. hardyi closely resembles the copper skink, Cyclodina aenea, and was considered to be a member of this species until recently when it was described as a new species using morphological, allozyme and DNA methods (Chapple et al. 2008).

O. hardyi is most commonly found in areas where there is ground cover near flax and scrub habitat.

It is crepuscular, seeking refuge during the day under stones or thick vegetation.

In addition, the midbody scale count is greater than that of the slight skink (Oligosoma levidensum) from the Te Paki region.