Shelley Henning

Hennig won the Miss Louisiana Teen USA 2004 in a state pageant held in Lafayette, Louisiana, in November 2003. This was the first time she competed in the state pageant. On August 6, 2004, Hennig represented Louisiana in the Miss Teen USA 2004, the pageant was held in Palm Springs, California. She won the Miss Teen USA title, becoming the first winner from Louisiana and the first girl from Louisiana to win a national title since Ali Landry was Miss USA 1996. Her Miss Teen USA winnings included a one year modeling contract with Trump Modeling Management, and a scholarship to The New York Conservatory for Dramatic Arts.

Her reign ended on August 8, 2005, when she crowned Allie LaForce of Ohio as the new Miss Teen USA.

On April 20, 2007, Hennig joined the cast of Days of Our Lives in the contract role of Stephanie Johnson. In 2010 she received a nomination for the 37th Daytime Emmy Awards in the Outstanding Younger Actress In A Drama Series category. On January 18, 2011, Hennig announced that she will be leaving Days of Our Lives. She was quoted in Soap Opera Digest saying:

Soon after she relinquished her crown, Hennig participated on MTV's The Reality Show where she attempted to win her own show, After the Crown but was eliminated. She hosted the Miss Teen USA 2008 pageant on August 16, 2008 along with co-host Seth Goldman.

From 2011 to 2012, she played the major character Diana Meade in the TV series The Secret Circle based on the books written by L. J. Smith. On May 11, 2012, it was announced that the series would not be returning for a second season. She then appeared in the MTV series Zach Stone Is Gonna Be Famous as Christy. On June 26, 2013, it was announced that the show was also canceled after one season.

Beginning in the third season, Hennig appeared as Malia Tate on the MTV series Teen Wolf. She was promoted to series regular for Season 4, and remained part of the show until it ended in 2017. For her portrayal of Malia, she won Choice Summer TV Star: Female at the 2016 Teen Choice Awards. In 2014, she appeared in the Blumhouse horror films Ouija and Unfriended.

She also appeared on The Band Perry's music video for "Gentle on My Mind" alongside The Hunger Games actor Alexander Ludwig. In 2017, she starred in country music artist Maren Morris' music video for "I Could Use a Love Song."

In 2018, she played supporting role as a photographer, Carrie Grey, in the Netflix romantic comedy When We First Met.

On March 10, 2020, it was reported that Hennig had been cast in an upcoming NBC Comedy pilot Crazy For You in a leading role. The pilot will be produced by Rachele Lynn who is known for her work in Saturday Night Live. The series' release date is unknown at this time.