In 2016 she was nominated for the Grammy Award for Song of the Year and won Best Country Song for co-writing the hit song "Girl Crush" performed by Little Big Town. In 2017 she again won Best Country Song at the 59th Annual Grammy Awards for "Humble and Kind" performed by Tim McGraw.
McKenna started writing songs as a teenager, and became a professional songwriter at the age of 27, when she was already married and had three children. She began singing at open mic nights in Boston, notably at the Blackthorn Tavern in nearby Easton, and eventually at her own shows. Working with her then manager Gabriel Unger, McKenna released four independent CDs: Paper Wings and Halo (produced by Seth Connelly), Pieces of Me (produced by Crit Harmon), The Kitchen Tapes (self-produced demos), and Bittertown (produced by Lorne Entress). During this period she recorded for Signature Sounds, won awards from ASCAP and the Boston Music Awards, performed at the Sundance Film Festival, the Newport Folk Festival and played many venues in the Northeast.
In 2004 McKenna signed a publishing deal with Nashville's Harlan Howard Music after Mary Gauthier shared McKenna's Bittertown with Melanie Howard. McKenna gained more attention in 2005, when Faith Hill recorded covers of four of McKenna's songs – three of which (including the title track) appeared on Hill's 2005 release Fireflies, the fourth as an exclusive to the iTunes Store.
McKenna parlayed her contribution to Hill's Fireflies into both an appearance on The Oprah Winfrey Show along with Hill, and a record deal with Warner Brothers Nashville. WB soon re-released McKenna's Bittertown on its label. In 2007, McKenna toured with Hill and Tim McGraw on the Soul2Soul Tour, accompanied by singer-songwriter/instrumentalist Mark Erelli and guitarist Russell Chudnofsky.
In addition to her own albums, McKenna has contributed a cover of Peter Gabriel's "In Your Eyes" to the 2005 "High School Reunion" compilation. In 2007, McKenna recorded a cover of Neil Young's "The Needle and the Damage Done" for the American Laundromat Records benefit CD Cinnamon Girl - Women Artists Cover Neil Young For Charity. Also, McKenna helped write "Most of Me", "Latest Mistake" and "Can't You Just Adore Her?" on Mandy Moore's album Wild Hope (2007), and "Everblue" on Amanda Leigh (2009). Lori McKenna's song "Bible Song" from Bittertown was recorded by country artist Sara Evans on her 'Real Fine Place' album released in 2005. Lori also contributed a song titled "I'm Workin'", recorded by Tim McGraw on his Let It Go album, released in 2007, as well as a song titled "True Believer", recorded by Jimmy Wayne on his 2008 album, Do You Believe Me Now.
Unglamorous, was released on August 14, 2007, on Warner Bros. Nashville and McGraw and Nashville producer Byron Gallimore’s label, Stylesonic Records. The album yielded two non-charting singles. McKenna parted ways with Warner Bros. in 2008.
UMPG Nashville signed McKenna to an exclusive publishing agreement. Her next album Lorraine was released on January 25, 2011 on Signature Sounds.
Her album, Massachusetts, was released on April 23, 2013.
In 2013, three songs co-written by McKenna entered the charts: "I Want Crazy" by Hunter Hayes, "Your Side of the Bed" by Little Big Town, and "Sober", also by Little Big Town.
In 2016, she became one of only five solo women (the others being Jennifer Nettles, Kimberly Perry, Gretchen Peters and K.T. Oslin) to win the CMA award for "Song of the Year" and the first woman to win two years in a row. In 2017, she became the first woman in the 52 year history of the ACM Awards to win "Songwriter of the Year".