Doubleday made her acting debut in an episode of the CBS procedural Without a Trace in 2002 and in the same year appeared in the feature film Catch Me If You Can. She graduated to supporting roles in films Waiting... (2005), The TV Set (2006) and Accepted (2006). In 2007, she starred in the ABC comedy series, Cavemen. The series received negative reviews and was canceled after a month on the air. In the following years, Doubleday continued performing on television, with small parts on CSI: Miami, Brothers & Sisters, Bones, The Closer, Criminal Minds, Drop Dead Diva and Witches of East End. Doubleday also performed in the recurring role of Logan Louis in the HBO comedy series Hung in 2011.
In 2015, Doubleday began starring in the Fox musical prime time soap opera, Empire. She plays Rhonda Lyon, wife of the eldest son in the Lyon family. Also in 2015, she was cast in the independent drama film Po directed by John Asher, about a single father raising a son with autism. Doubleday also appeared as a Celebrity guest on The CW improvisational comedy show Whose Line Is It Anyway in June 2016. In 2017, she featured in the popular horror series Scary Endings alongside Australian actor Adam J. Yeend in an episode titled "The Water Rises".
In May 2015, Doubleday became engaged to DJ Devin Lucien in Paris. She and Lucien married on May 6, 2016 in Big Sur.
In 2017, Doubleday joined the cast of CMT musical drama series Nashville in its fifth season, following the departure of original series star Connie Britton. She portrays Jessie Caine, a singer/songwriter. Her character was introduced during the series' 100th episode on June 15, 2017.
