  We study the effect of the gravitational Chern-Simons term (GCST) in the
(2+1)-dimensional anti-de Sitter (AdS$_{2+1}$) geometry. In the context of the
gauge gravity, we obtain black hole solution and its boundary WZW theory. The
BTZ black hole solution can still be retrieved but its gravitational mass and
angular momentum become different from their inherent values. The deformation
on these quantities due to the GCST can be summarized as $SO(1,1)$ times
rescaling. The boundary WZW theory is found to be chiral, i.e., composed of the
right moving part and the left moving part with different Kac-Moody levels. The
statistical entropy is proportional to the area only for the large levels and
vanishing GCST limit, but its coefficient is not the correct order in the
Newton constant $G$. Some related physics are discussed.
