185 Eunike is a dark and very large main-belt asteroid, with an approximate diameter of 157 kilometres.

The name was chosen to celebrate the Treaty of San Stefano (1878).

Based upon photometric observations made between 2010 and 2014, this asteroid has a rotation period of 21.812 ± 0.001 hours and a brightness variation of 0.08 ± 0.01 in magnitude.

It displays a hemispheric albedo dichotomy similar to that on 4 Vesta.

[4] As of 17 September 2020, there have been thirteen observed occultations of stars by Eunike.