Sunday night's opener marked the network's highest-rated drama premiere in its 50-year history, with viewership up 29 percent from last season.
"I'm delighted to see that the Crawley family's intrigue continues to beguile our viewers," Masterpiece executive producer Rebecca Eaton said in a statement. "[Showrunner] Julian Fellowes has written every word of all four seasons of Downton, and I toss him a huge bouquet on behalf of his American fans."
Rosie O'Donnell unveils nearly 50-pound weight loss
Justin Bieber crashes Drake Bell's album release party