The final season will consist of 10, one-hour episodes and will focus on the British monarch's tumultuous relationships with his last two wives, Catherine Howard and Catherine Parr, as well as his final descent into madness, the cable network said in a news release.
Season 4, which will return in spring 2010, will be written by series creator and executive producer Michael Hirst, with production to begin this June in Dublin, Ireland.
Hirst will have single-handedly written all 38 of the series' one-hour episodes by the time the story is complete.
"I'm thrilled to complete the saga of Henry VIII as re-conceived by Michael Hirst. He and Jonathan Rhys Meyers have breathed new life into the costume drama by making it both modern in sensibility but also faithful to history. I think we proved that even after 500 years this is a great story," Robert Greenblatt, president of entertainment for Showtime, said in a statement.
Season 3 of "The Tudors" began April 5.