We study matter-coupled N = 3 gauged supergravity in four dimensions with various semisimple gauge groups. When coupled to n vector multiplets, the gauged supergravity contains 3 + n vector fields and 3n complex scalars parametrized by SU(3, n)/SU3) x SU(n) x U(1) coset manifold. Semisimple gauge groups take the form of G(0) x H subset of SO(3, n) subset of SU(3, n) with H being a compact subgroup of SO(n + 3 - dim(G(0))). The G(0) groups considered in this paper are of the form SO(3), SO(3, 1), SO(2, 2), SL(3, R) and SO(2, 1) x SO(2, 2). We find that SO(3) x SO(3), SO(3, 1) and SL(3, R) gauge groups admit a maximally supersymmetric AdS(4) critical point. The SO(2, 1) x SO(2, 2) gauge group admits a supersymmetric Minkowski vacuum while the remaining gauge groups admit both half-supersymmetric domain wall vacua and AdS(4) vacua with completely broken supersymmetry. For the SO(3) x SO(3) gauge group, there exists another supersymmetric N = 3 AdS(4) critical point with SO(3)(diag) symmetry. We explicitly give a detailed study of various holographic RG flows between AdS(4) critical points, flows to nonconformal theories, and supersymmetric domain walls in each gauge group. The results provide gravity duals of N = 3 Chern-Simons-matter theories in three dimensions.