Abstract: A cooler sleeve assembly includes a cooler that has an outer wall and a lid. The cooler is comprised of a thermally insulating material for storing temperature sensitive materials. A sleeve is positionable around the cooler and the sleeve is comprised of a thermally insulating material for increasing thermal insulation properties of the cooler. A cover is hingedly coupled to the sleeve and the cover is positionable between a first position and a second position. The cover is comprised of a thermally insulating material and the cover lies on the lid of the cooler when the sleeve is positioned around the cooler and the cover is positioned in the first position. The cover extends upwardly from the cooler when the sleeve is positioned around the cooler and the cover is positioned in the second position for opening the lid to access an interior of the cooler.