NASA's Wide-field Infrared Survey Explorer (WISE; Wright et al. 2010) mapped the sky at 3.4, 4.6, 12, and 22 μm (W1, W2, W3, W4) in 2010 with an angular resolution of 6.1", 6.4", 6.5", & 12.0" in the four bands. WISE achieved 5σ point source sensitivities better than 0.08, 0.11, 1 and 6 mJy in unconfused regions on the ecliptic in the four bands. Sensitivity improves toward the ecliptic poles due to denser coverage and lower zodiacal background.The All-Sky Release includes all data taken during the WISE full cryogenic mission phase, 7 January 2010 to 6 August 2010, that were processed with improved calibrations and reduction algorithms. Release data products include an Atlas of 18,240 match-filtered, calibrated and coadded image sets, a Source Catalog containing positional and photometric information for over 563 million objects detected on the WISE images, and an Explanatory Supplement that is a guide to the format, content, characteristics and cautionary notes for the WISE All-Sky Release products.