Air date: 2009-12-14

The first season of The Sing-Off premiered on December 14, 2009. The show featured eight a cappella groups performing popular songs live. The winner's prize was $100,000 and a Sony Music recording contract. Nick Lachey hosted, while Ben Folds of Ben Folds Five, Shawn Stockman from Boyz II Men and Nicole Scherzinger from The Pussycat Dolls were judges. The show ran for 4 episodes, concluding on December 21, 2009 with a live finale. The group Nota won the title.

Air date: 2010-12-06

The second season of The Sing-Off premiered on December 6, 2010. The number of a cappella groups was increased from 8 to 10, with all acts coming from the United States. Nick Lachey was kept as host for the new season, and the three judges Ben Folds, Shawn Stockman and Nicole Scherzinger also returned. The program aired for 5 nights in December, and its finale was on December 20, 2010. The season premiere averaged 8.5 million viewers. On the finale, the group Committed became the second champion of the show, beating out Street Corner Symphony, The Backbeats, and Jerry Lawson & Talk of the Town. This was Scherzinger's final season as a judge.

Air date: 2011-09-19

The third season of The Sing-Off premiered on September 19, 2011. The number of a cappella groups was increased from 10 to 16, resulting in a new format. The show created two brackets, with only half the groups performing each week for the first few weeks. Nick Lachey stayed as host for the new season, as did Ben Folds and Shawn Stockman as judges. New to the judges' table was Sara Bareilles, who replaces Nicole Scherzinger, who left after 2 seasons to become a judge on The X Factor. The program ran for 11 episodes, and was concluded on November 28, 2011 with Pentatonix winning the title.

Air date: 2013-12-09

The fourth season of The Sing-Off returned with the number of a cappella groups competing decreased from sixteen back to ten, resulting in a new format. Nick Lachey remained as host for the new season, with Ben Folds and Shawn Stockman returning as judges. New to the judges' table was Jewel, who replaced Sara Bareilles. A group was eliminated from the show each week in a new feature called the "Ultimate Sing-Off," where the two groups ranked lowest at the end of each episode would compete by singing the same song; the groups take turns alternating verses before ending the song singing together. Also, unlike previous seasons, the winner was chosen by the judges instead of by the general public.

Air date: 2014-12-17