The unpolarized semi-inclusive deep-inelastic scattering (SIDIS) differential cross sections in He-3(e, e'pi') X have been measured for the first time in Jefferson Lab experiment E06-010 with a 5.9 GeV e(-) beam on a He-3 gas target. The experiment focuses on the valence quark region, covering a kinematic range 0.12 < x(bj) < 0.45, 1 < Q(2) < 4 (GeV/c)(2), 0.45 < z(h) < 0.65, and 0.05 < P-t < 0.55 GeV/c. The extracted SIDIS differential cross sections of pi(+/-) production are compared with existing phenomenological models while the He-3 nucleus approximated as two protons and one neutron in a plane-wave picture, in multidimensional bins. Within the experimental uncertainties, the azimuthal modulations of the cross sections are found to be consistent with zero.