LaMontagne's second album, Till the Sun Turns Black, was released in August 2006 and featured horn and string sections on several of the songs with Rachael Yamagata providing additional vocals on the song "Barfly". The album peaked at No. 28 on the Billboard 200 album chart, selling 28,000 copies in its first week of release. The album spawned the single "Three More Days". In 2006 LaMontagne performed on The Tonight Show.
The song "Till the Sun Turns Black" was featured on the television show ER, and the songs "Lesson Learned" and "Within You" appeared on the CW drama One Tree Hill. His song "Be Here Now" was heard on the trailer for the movie Away From Her, in the film 27 Dresses, on the TV shows Bones, Covert Affairs and Brothers & Sisters. LaMontagne performed at KYSR's Lounge for Life charity concert on October 5, 2006, at the House of Blues in West Hollywood, California. He also auctioned off one of his guitars on eBay for its charity auction. Funds raised from the concert and auction went to breast cancer research.
For his debut album, LaMontagne won four awards, including three Boston Music Awards (Best Male Singer-Songwriter, Album of the Year, and Song of the Year) and an XM Nation Music Award for Acoustic Rock Artist of the Year. LaMontagne has received a nomination from the Pollstar Concert Industry Awards for Best New Touring Artist, the BRIT Awards for International Breakthrough Act, the MOJO Awards for Best New Act, and was given the title of Best Voice in 2006 by Esquire.