We present our measurements of the Hα, [Oiii], and [Oii] luminosity functions as part of the Lyman Alpha Galaxies at Epoch of Reionization (LAGER) survey using our samples of 1577 z = 0.47 Hα-, 3933 z = 0.93 [Oiii]-, and 5367 z = 1.59 [Oii]selected emission line galaxies in a 3 deg 2 single, CTIO/Blanco DECam pointing of the COSMOS field. Our observations reach 5σ depths of 8.2 × 10 −18 erg s −1 cm −2 and comoving volumes of (1 − 7) × 10 5 Mpc 3 making our survey one of the deepest narrowband surveys. We select our emission line galaxies via spectroscopic confirmation, photometric redshifts, and color-color selections. We measure the observed luminosity functions for each sample and find best-fits of φ = 10 −3.16 +0.09 −0.09 Mpc −3 and L = 10 41.72 +0.09 −0.09 erg s −1 for Hα, φ = 10 −2.16 +0.10 −0.12 Mpc −3 and L = 10 41.38 +0.07 −0.06 erg s −1 for [Oiii], and φ = 10 −1.97 +0.07 −0.07 Mpc −3 and L = 10 41.66 +0.03 −0.03 erg s −1 for [Oii], with α fixed to −1.75, −1.6, and −1.3, respectively. An excess of bright > 10 42 erg s −1 [Oiii] emitters is observed and may be due to AGN contamination. Corrections for dust attenuation are applied assuming A Hα = 1 mag. We also design our own empirical rest-frame g − r calibration using SDSS DR12 data, test it against our z = 0.47 Hα emitters with zCOSMOS 1D spectra, and calibrate it for (g − r) between −0.8 and 1.3 mag. Dust and AGN-corrected star formation rate densities (SFRDs) are measured as log 10 ρ SFR /(M yr −1 Mpc −3 ) = −1.63 ± 0.04, −1.07 ± 0.06, and −0.90 ± 0.10 for Hα, [Oiii], and [Oii], respectively. We find our [Oiii] and [Oii] samples fully trace cosmic star formation activity at their respective redshifts in comparison to multi-wavelength SFRDs, while the Hα sample traces ∼ 70 percent of the total z = 0.47 SFRD.