[4] As a child, Michaelson performed in a musical theatre group called Staten Island Kids On Stage.

She continued piano at the Jewish Community Center of Staten Island's Dorothy Delson Kuhn Music Institute.

[6] Michaelson is a graduate of Staten Island Technical High School and Binghamton University, where she received a degree in theater.

While living on Staten Island and mainly busking in Lower Manhattan, Michaelson self-released her debut album Slow the Rain on January 10, 2005.

Michaelson and Bareilles performed "Winter Song" for Barack Obama and his family at the National Christmas Tree Lighting in December 2010.

[citation needed] It features the single "Maybe".In 2010, Michaelson co-wrote the song "Parachute" with Marshall Altman for British singer Cheryl Cole.

In 2012, with her husband and fellow musician Greg Laswell, Michaelson co-wrote and sang the duet "Landline", which appeared on his album of the same name.

In September 2012, she was featured in a campaign called "30 Songs / 30 Days" to support Half the Sky: Turning Oppression into Opportunity for Women Worldwide, a multi-platform media project inspired by Nicholas Kristof and Sheryl WuDunn's book.

[14] It served as the lead single from her seventh studio album, It Doesn't Have to Make Sense, which was released on August 26, 2016.

[15] In July, she released a second video of "Hell No," which incorporates members of the Deaf West theater company performing the lyrics in American Sign Language.

[20] Michaelson made her Broadway debut playing the role of Sonya Rostova in the musical Natasha, Pierre & The Great Comet of 1812 from July 3 to August 13, 2017.

In July 2020, Michaelson was nominated for her first Emmy Award in the Outstanding Original Music and Lyrics category for the song "Build it Up", written specifically for the finale of Hulu's hit miniseries Little Fires Everywhere.

[29][30] Michaelson partnered with collaborators Juan Ariza and Gabriel Mann to compose an original song "Not Gone," a cover of "Closer to Fine" and the score for the Hulu miniseries Tiny Beautiful Things.

[31] Michaelson served as executive music producer for Apple TV+’s Slumberkins, creating original songs for the series with her bandmates Allie Moss, Hannah Winkler, and Billy Libby.

Later that year, Michaelson collaborated with A Great Big World on an original song called "It's Almost Christmas", released on November 11, 2022.

[38] In 2024, Michaelson made a guest appearance in season 3 of Netflix's Girls5eva, playing the role of Pixie, a folk singer-songwriter.

[39] Michaelson released a string of singles from her album For the Dreamers, including "Love Is" with Jason Mraz on February 2,[40] a cover of the song "What a Wonderful World" on May 23, and "It Never Ends" on May 30.