Michael Grant from Michael's Winx Club says that at the Licensing Show it was confirmed that the series will continue into a fifth season! The NewsPage said:
"This is not a rumor as the official news was given directly to me and is already being planned in Italy. There is no official data at this time on storylines, etc. as Season 4 is still in the works, but Winx Club Season 5 is definitely approved."
This was written in 2009, over two years ago. Keep that in mind before you comment.