The season will include eight episodes and an extended Christmas 2013 special. It is to begin shooting at England's Highclere Castle and Ealing Studios in February, the British network said.
"The opening and closing episodes will again be feature-length with Series 4 continuing the story of the Crawley family and their servants in the early 1920s," a synopsis said.
"Viewers can look forward to more drama, comedy, love, hatred, jealousy, rivalry, ambition, despair and romance," Gareth Neame, managing director of Carnival Films -- the show's makers -- and executive producer of "Downton Abbey," said in a statement.
"We're thrilled to welcome back a drama series that has become a much anticipated part of all our lives every autumn and achieved success around the globe," said Laura Mackie, ITV's director of drama. "Creator, writer and executive producer Julian Fellowes and the production team, led by Gareth and the producer Liz Trubridge, never rest on their laurels and have exciting plans for the fourth series."
Starring Hugh Bonneville and Maggie Smith, the program recently wrapped up its third season on ITV. Season 3 is to premiere in the United States Jan. 8 on PBS.