The network announced this week that the trio of alternative programmes had been renewed for the upcoming 2011-2012 television season.
"Alternative series such as these three bona fide hits are important not only to their loyal audiences but also as strong components of the NBC schedule," said NBC Entertainment chairman Bob Greenblatt.
"They are each unique, attention-getting shows with terrific producing and talent auspices, and we're proud to be associated with them."
The Biggest Loser is currently airing its 11th season on Tuesday nights, while Who Do You Think You Are?, which is executive produced by Lisa Kudrow, premiered its second season earlier this year. A cappella competition The Sing-Off, hosted by Nick Lachey, wrapped its sophomore season in December.