This was Stewart's fifth attempt at the Miss Texas USA title; she had placed first runner-up in both the 2006 and 2007 events; third runner-up in 2005; and made the semi-finals in 2003. Her first appearance in the state pageant was in 2002 when she made the semi-finals of the Miss Texas USA 2003 pageant competing as Miss Fort Bend County. In 2004, Stewart again competed as Miss Fort Bend County and placed third runner-up to Tyler Willis at Miss Texas USA 2005. The following year she competed in the Miss Houston local pageant and placed first runner-up to Lauren Lanning. She competed at Miss Texas USA 2006 as Miss Harris County, and placed first runner-up to Lanning for the second time. In 2006, she placed first runner-up to Miss Houston for a second time and, in a double repetition, placed first runner-up to Miss Houston, Magen Ellis, in the 2007 state pageant (competing as Miss Southeast Texas).
In 2007 she did not compete for a local title, and instead entered as an at large delegate for Miss Texas USA 2008, again holding the Miss Fort Bend County title. She made the final two in the state-televised pageant, alongside Miss Houston Brooke Daniels, who was also a runner-up at Miss Texas USA 2007. This time Stewart won the title and was crowned Miss Texas USA 2008. She also won the Everything but Water Swimsuit award, announced during the preliminary competition. Stewart is the second African American to win the crown at Miss Texas USA; Chelsi Smith was crowned Miss Texas USA 1995 (and later Miss USA and Miss Universe).
On July 13, 2008, Stewart represented the USA at the Miss Universe pageant Nha Trang, Vietnam, and advanced to the top 10. Stewart became the second consecutive Miss USA, following Rachel Smith in 2007, to stumble and fall during the evening gown competition. After that, she encouraged the audience to applaud by clapping her hands. Unlike Smith, Stewart did not advance to the top five. Stewart finished 8th overall.
Stewart hosted the Miss Teen USA 2009 competition on July 31, 2009 along with Seth Goldman. On July 24, 2010, Goldman and Stewart once again hosted the Miss Teen USA pageant.
Stewart also co-hosted multiple Miss Texas USA pageants including some with her Belgian-born husband, model Max Sebrechts (married August 9, 2014), and she also co-hosted with Jason Feinberg.
Stewart served as a finals judge at the Miss USA 2016 pageant on June 5, 2016 in Las Vegas, Nevada.
