In addition to lending her sultry vocals to the albums O and 9, she also toured with Rice, bolstering his music with her multi-instrumental talents on the guitar, keyboards, and drums. Hannigan sometimes performed her own songs, traditional tunes, or the occasional cover at the shows, as well.

On March 26, 2007, Rice informed Hannigan that his professional relationship with her was over, citing his opinion that the partnership "has run its creative course." Undaunted, Hannigan began preparing her own folk songs for the studio, releasing demos on her MySpace page as they trickled out. In 2008, she hit the road as the opener for Jason Mraz's U.S. and Canadian tour, and her debut solo effort, Sea Sew, was released in Ireland later that year, with an American release following in early 2009. The album went double platinum in Hannigan's homeland, where her whimsical folk-pop and hushed, soft-spoken vocal delivery appealed to critics and consumers alike. She explored similar territory on her Joe Henry-produced, 2011 sophomore release, Passenger, which again drew accolades both at home and abroad. After touring for two years in support of the album, Hannigan experienced a lengthy bout of writer's block. She returned in 2016 with a new album, At Swim, which was produced by the National's Aaron Dessner. ~ James Christopher Monger