In 2004, Ari Martin of Nettwerk Management became Lightman’s manager. After seeing Lightman play a solo showcase for record executives and representatives, Jason Flom signed Lightman to Lava Records, a subsidiary of Atlantic Records. Lightman released her debut Little Things through Lava on March 30, 2004. The Album was produced by Peter Zizzo. A second version of Little Things was released on July 20, 2004 that included a bonus cover track of Mary J. Blige’s 1992 hit single Real Love. The song was released as the album’s second single and a music video was filmed to promote the track.
In late 2005, Lightman appeared on Lava Records label mates O.A.R.'sStories of a Stranger. On that album, which peaked at number 40 on the Billboard 200, Lightman sang alongside O.A.R. frontman Marc Roberge on the track "The Stranger". Lightman was then featured as a VH1You Oughta Know artist and as an MTVYou Hear It First artist. She also appeared on such shows as Late Show with David Letterman, Late Night with Conan O'Brien, CBS's Morning show Second Cup, ESPN's Cold Pizza, A&E's Breakfast with the Arts and various others.
Bird On A Wire, Lightman's second record was released on July 25, 2006 on Atlantic Records. "My Sweet Song" from Bird On A Wire was featured near the end of the Boston Legal episode, "Desperately Seeking Shirley" while also featuring in the closing scene of the Bones (TV Series) episode, "The Maggots In The Meathead". It was also featured in the soundtrack to the movie P.S. I Love You. The song "Slippin'" appeared on ABC's Brothers & Sisters. Lightman performed the opening theme to Fox Sports' coverage of the NASCAR racing season with a song titled "NASCAR Love (Let's Go Racing)".
Lightman released her third album, Let Go on her own T Killa Records label on July 15, 2008. The album is being sold through digital retailers like iTunes and amazon.com. The album will also be available for sale through the Home Shopping Network. The song "Let Go" & "One Day" from Let Go will be featured in a series of commercials to air on HSN. The song "Let Go" has also appeared on ABC's Brothers & Sisters and Dirty, Sexy, Money. A new song "Color" is on a new benefit compilation that was released by the Hard Rock Cafe and the folks from World Hunger Year.
On June 5, 2010, Lightman released her fourth album, Know Where I'm From also on her T Killa Records label. This album contains 11 acoustic versions of her previously released songs.
In 2011, Lightman's new song "Holding a Heart" was featured in the film What's Your Number?, credited to "Girl Named Toby". Also, another new song "Addicted" by Lightman was never released as an official single, but was featured as a promo of the twelfth episode from the eighth season of Desperate Housewives and in the television film Mean Girls 2. Lightman subsequently released the song under her own name on her five-song EP Holding a Heart in 2013.