Mattress assemblies are provided that include a mattress, a mattress overlay, and a mattress cover that is comprised of a first cover and a second cover. The first cover includes a top panel, a bottom panel, and a continuous side panel that collectively define a cavity and enclose the mattress. The mattress overlay is positioned atop the mattress and the first mattress cover. The second cover, which defines a perimeter, is positioned over and is dimensionally-sized to cover the mattress overlay and at least the top panel of the first cover. The second cover can then be connected to the first cover by a fastener that extends along the perimeter of the second cover.