  We present a spinning hairy black hole in gravity minimally coupled to a
self-interacting real scalar field in three spacetime dimensions. The black
hole is characterized by having a single horizon which encloses a curvature
singularity and the scalar field is regular everywhere. The mass and angular
momentum are shown to be finite. The presence of a scalar field with a slower
fall-off at infinity leads an anti-de Sitter asymptotic behavior which differs
from the one found by Brown and Henneaux, but has the same symmetry group as in
pure gravity. A scalar soliton, which is a finite mass regular solution devoid
of integration constants, plays the role of the ground state. The existence of
this soliton is the key to derive the semiclassical entropy of the rotating
hairy black hole using the counting of microscopic states provided by the Cardy
formula.
