Abstract: A lawn chair rocker base system for converting a lawn chair having four legs that support a seat into a rocking chair. The lawn chair rocker base system includes a rocker base assembly and a chair locking structure. The rocker base assembly includes two rocker members that are spaced apart and secured together by two rigid spacer bars, each rocker member including a curved rocker rail and two chair foot receiving structures, each chair foot receiving structure including a planar chair foot receiving surface and a chair foot insertion opening formed through two rigid plates oriented at right angles to each other and at a right angle to the planar foot receiving surface.