A stake pocket anchor attaches an accessory to a vehicle stake pocket. The stake pocket anchor includes an anchor assembly hung from a tensioning member. The anchor assembly includes two channel members slidably attached to sandwich a center block, with an angled slide direction that enables sliding either upwardly and inwardly to a minimum anchor assembly width or downwardly and outwardly to a maximum anchor assembly width. During use, the anchor assembly gravitationally releases to its maximum anchor assembly width after being inserted through the stake pocket opening. The tensioning member is then used to vertically raise the anchor assembly within the stake pocket until a top of the anchor assembly contacts a bottom surface of the lip and thereafter allows further tightening of the anchor assembly against the bottom surface of the lip.