The film, from director Greg Whiteley ("New York Doll"), will make its debut Jan. 17 at the Sundance Film Festival in Salt Lake City. It follows the candidate from his initial quest to become the GOP's nominee in 2008 through his concession speech in 2012.
The Netflix news followed an announcement, earlier Monday, that "Mitt" would be among several films premiering at the 2014 festival.
Whiteley was given broad access to Romney and his family. The filmmaker traveled with the campaign, following the candidate's interactions with potential voters, his preparations for the debates, private moments with the family and the election night results.
"This rare inside look at Mitt Romney and his family, as he runs for president, showcases a unique kind of storytelling, one which takes the viewer well beyond politics," Lisa Nishimura, Netflix's vice president of original documentary and comedy, said in a statement.
Netflix will make the documentary available Jan. 24 to its subscribers in the U.S., Canada, the U.K., Ireland, Latin America, Nordic countries and the Netherlands.
The budding Internet television service said earlier this year that it would broaden its original program offerings beyond scripted dramas, such as the acclaimed "House of Cards" and "Orange Is the New Black," to include documentary films.
In November, it said it had acquired the rights to "The Square," a political film that centers on real-life protesters in Cairo's Tahrir Square.