Winx Club is an animated television series co-produced by Rainbow SpA and later Nickelodeon. It was created and directed by Italian animator Iginio Straffi. It premiered on 28 January 2004, becoming a ratings success in Italy and on Nickelodeon networks internationally. The show is set in a magical universe that is inhabited by fairies, witches, and other mythical creatures. The main character is Bloom, a girl from planet Earth who discovers she's a fairy and enrolls at Alfea College to train and hone her magical skills. At Alfea, she makes friends with four other fairies with whom she founds a group called the Winx Club, and together, they fight a long series of enemies who threaten the Magic Dimension, discovering in the process her true origins and the fate of her biological family. The series uses a serial format with an ongoing storyline.

Iginio Straffi initially outlined the show's plot to last three seasons. He chose to continue the story for a fourth season in 2009. Around this time, Winx Club's popularity attracted the attention of the American media company Viacom, owner of Nickelodeon. Viacom purchased 30% of the show's animation studio, Rainbow SpA, and Nickelodeon began producing a revival series. Production on the fifth, sixth, and seventh seasons was divided between Rainbow and Nickelodeon Animation Studio. To attract an American audience, Viacom assembled a voice cast of Nickelodeon actors (including Elizabeth Gillies and Ariana Grande), invested US$100 million in advertising for the series, and inducted Winx Club into Nickelodeon's franchise of Nicktoons.

Beginning in 2010, episodes of Winx Club were jointly written with Nickelodeon's American team. Nickelodeon's writers aimed to make the series multicultural and appealing to viewers from different countries. In 2019, Straffi commented on his years of collaboration with Nickelodeon, saying that "the know-how of Rainbow and the know-how of Nickelodeon are very complementary; the sensibilities of the Americans, with our European touch." The continued partnership between Rainbow and Nickelodeon on Winx Club led to the development of more co-productions, including Club 57 in 2019, on which much of Winx Club's staff worked.

The series was subject to budget cuts in 2014, during its seventh season; the 3D computer-generated segments and Hollywood voice actors were deemed too costly. The seventh season eventually premiered on Nickelodeon's worldwide channels in 2015. After a four-year hiatus, an eighth season premiered in 2019. At Straffi's decision, this season was heavily retooled for a preschool target audience.

A live-action adaptation of Winx Club for young adults, titled Fate: The Winx Saga, premiered in 2021. In January 2023, Viacom (now known as Paramount Global) sold its stake in Rainbow SpA back to Straffi, allowing him full control of the studio's new projects, including an upcoming animated reboot of the Winx Club franchise.