Raymund was born in St. Petersburg, Florida to Steve Raymund, the board chairman and retired CEO of Tech Data Corp., a Clearwater-based distributor of computer components and software, and Sonia (née Lara), "a community volunteer [and the] co-founder of the Soulful Arts Dance Academy in St. Petersburg," who hails from Santo Domingo, Dominican Republic. Her father was of German and Eastern European Jewish descent. Her grandfather was businessman and philanthropist Edward C. Raymund. Raymund's younger brother, Will was a graduate of Berklee College of Music, and a sound and lighting engineer and music promoter. He died in August 2015. She was raised Jewish and celebrated a bat mitzvah. In high school, she participated in the "Broadway Theater Project in Tampa and at the North Carolina School of the Arts in Winston-Salem."
Raymund graduated from Shorecrest Preparatory School in St. Petersburg, Florida in 2004, and from the Juilliard School in New York City in 2008.
Reportedly, Raymund performed in Cymbeline directed by Richard Feldman, The Diviners (directed by Jonathan Bernstein), and Animal Farm (directed by Trizana Beverley) all at the Juilliard School.
Raymund also appeared in her native St. Petersburg, Florida in the LiveArts Peninsula Foundation's original production of Manhattan Casino (directed by Bob Devin Jones) where she originated the leading role of Althea Dunbar and Webb's City: The Musical (music & lyrics by Lee Ahlin, written and directed by William Leavengood)." Raymund "is a three-year alumna of Ann Reinking's Broadway Theater Project, where she has been a featured performer."
Raymund has also "worked with playwright José Rivera on Boleros for the Disenchanted at the Huntington Theatre Company in Boston" in 2008. In April 2008, she appeared the NBC legal drama Law & Order: Special Victims Unit, in season 9 episode 17 titled "Authority" in the opening scene as a strip search prank call victim. From 2009 to 2011, she starred in the Fox police drama Lie to Me, where she played Maria "Ria" Torres, a human lie detector who is a "natural", meaning she has no formal training in detecting lies or the emotions of others. She was using crutches because of a knee injury when she auditioned for this role.
From 2011 until 2012, Raymund had a recurring role in the third season of the CBS legal drama The Good Wife, where she played Dana Lodge, an assistant states attorney.
In 2012, Raymund began starring in the NBC drama Chicago Fire as Gabriela Dawson Casey, the paramedic in charge.
On June 11, 2011, Raymund married writer Neil Patrick Stewart. Raymund and Stewart separated in early 2013 and divorced in 2014.
Raymund is an ardent supporter of LGBT rights. In February 2014, she came out publicly as bisexual for the first time via Twitter. Before that, she had been out privately for over ten years. On September 16, 2015, Raymund announced via Twitter that she had begun dating Tari Segal.