The 2018 Jersey Flegg Cup season was the 48th season of the under-20 competition and the first since 2007. The competition, administered by the New South Wales Rugby League, replaced the National Rugby League's National Youth Competition, and mirrored the draw and structure of its senior counterpart, the Intrust Super Premiership. The Cronulla-Sutherland Sharks defeated the Penrith Panthers in the Grand Final, winning their first Jersey Flegg Cup premiership.