Abstract We present a new data release from the Fiber Multi-Object Spectrograph (FMOS)-COSMOS survey that contains the measurements of the spectroscopic redshift and flux of rest-frame optical emission lines (Hα, [N ii], [S ii], Hβ, [O iii]) for 1931 galaxies out of a total of 5484 objects observed over the 1.7 deg2 COSMOS field. We obtained H- and J-band medium-resolution (R ∼ 3000) spectra with FMOS mounted on the Subaru telescope, which offers an in-fiber line flux sensitivity limit of for an on-source exposure time of 5 hr. The full sample contains the main population of star-forming galaxies at z ∼ 1.6 over the stellar mass range , as well as other subsamples of infrared-luminous galaxies detected by Spitzer and Herschel at the same and lower (z ∼ 0.9) redshifts and X-ray-emitting galaxies detected by Chandra. This paper presents an overview of our spectral analyses, a description of the sample characteristics, and a summary of the basic properties of emission-line galaxies. We use the larger sample to redefine the stellar mass–star formation rate relation based on the dust-corrected Hα luminosity and find that the individual galaxies are better fit with a parameterization including a bending feature at M * ≈ 1010.2 M ⊙, and that the intrinsic scatter increases with M * from 0.19 to 0.37 dex. We also confirm with higher confidence that the massive (M * ≳ 1010.5 M ⊙) galaxies are chemically mature as much as local galaxies with the same stellar masses, and that the massive galaxies have lower [S ii]/Hα ratios for their [O iii]/Hβ as compared to local galaxies, which is indicative of enhancement in the ionization parameter.