Winx Club: The Secret of the Lost Kingdom (Italian: Winx Club - Il segreto del regno perduto) is a 2007 Italian animated fantasy film directed and co-written by Iginio Straffi. It is an adaptation of the animated television series Winx Club, taking place after the events of the first three seasons.

The film was released in Italy on 30 November 2007, by 01 Distribution. It was released theatrically from the same date onwards in select regions. In the United States, the film premiered direct-to-television on Nickelodeon on 11 March 2012, following the channel's parent company Viacom becoming a co-owner of Rainbow S.p.A.