The Hubble constant H0 and matter density m of the universe are measured using the latest γ-ray attenuation results from Fermi-LAT and Cerenkov telescopes. This methodology is based upon the fact that the extragalactic background light supplies opacity for very high energy photons via photon-photon interaction. The amount of γ-ray attenuation along the line of sight depends on the expansion rate and matter content of the universe. This novel strategy results in a value of km s−1 Mpc−1 and . These estimates are independent and complementary to those based on the distance ladder, cosmic microwave background (CMB), clustering with weak lensing, and strong lensing data. We also produce a joint likelihood analysis of our results from γ-rays and those from more mature methodologies, excluding the CMB, yielding a combined value of H0 = 66.6 1.6 km s−1 Mpc−1 and m = 0.29 0.02.