After graduation, he moved to New York City to pursue an acting career. Though he landed a part on the soap opera "Another World" in 1990, he moved to Los Angeles the next year where he had small parts in In Living Color, a Roger Corman film, Hard Run, and in music videos. While taking classes on screenwriting at UCLA he wrote his first script, Killing Mrs. Tingle which was bought by a production company in 1995 and put on the shelf.
Inspired by the March 9, 1994 episode of the newsmagazine Turning Point on Danny Rolling, a serial killer in Gainesville, Florida who preyed on college students, Williamson wrote a horror movie script, originally titled "Scary Movie". Its characters had seen many classic horror movies (e.g. A Nightmare on Elm Street, Halloween) and knew all the clichés. Miramax bought it for their new Dimension Films label in the spring of 1995. Directed by Wes Craven, the film was renamed Scream, and released in The United States on December 20, 1996. It became a commercial blockbuster and critical success—ultimately drawing $173 million in ticket sales worldwide.
Kevin Williamson earned the Saturn Award for Best Writing in 1996 for his work on Scream.
Miramax later released Scream 2, also written by Williamson, It, too, was a hit and paved the way for Scream 3, the third installment of the Scream trilogy.
Williamson was the writer and producer for Scream 4, which began shooting in June 2010 and was released in theaters on April 15, 2011.
Paul Stupin, an executive at Columbia Tri-Star Television, read Scream after the bidding war for the script and was convinced Williamson was just the man to create a television series for his company. The result was Dawson's Creek, a semi-autobiographical tale set in a small coastal community not unlike Oriental. Williamson was the model for the title character, Dawson Leery, a hopeless romantic who is obsessed with movies—especially those of Steven Spielberg. Joey Potter, the platonic girl-next-door, was based on a real life friend of Williamson's when he was young.
In December 1995, the show was pitched to the Fox Network, where Stupin had been an executive, but it was rejected. Then in 1996, Stupin and Williamson went to, and struck a deal with, The WB. Williamson said, "I pitched it as Some Kind of Wonderful, meets Pump Up the Volume, meets James at 15, meets My So-Called Life, meets Little House on the Prairie." Dawson's Creek premiered on The WB on January 20, 1998, and was an immediate hit with its intended audience.
Despite the show's success (and telling Entertainment Weekly that "[I] ain't never leaving 'Dawson's Creek'."), Williamson left the show at the end of its second season to create a show for Miramax to air on ABC. The result, Wasteland, about twentysomethings in New York City, was savaged by critics. The Hollywood Reporter said it was about "the most attractively vacuous, self-indulgent, and pretentious group ever assembled in prime-time." It aired only three episodes in October 1999 before being canceled by ABC.
Williamson returned to Dawson's Creek to pen the two-part series finale in 2003.
Williamson's next film, I Know What You Did Last Summer, was also about young adults in peril. Based on a 1973 novel by Lois Duncan, it centered around four friends accidentally running over a man, dumping the body, and going on with their lives, only to be punished one year later.
Columbia Studios advertised the film as "from the makers of Scream" against Miramax's wishes, who later sued the company.
Williamson's first script was only produced when Williamson himself got behind the camera to direct. Starring Dawson's Creek's Katie Holmes, Barry Watson, and Helen Mirren, Teaching Mrs. Tingle (as it was renamed after the Columbine High School Massacre), had two students getting even with their vindictive teacher. Despite the cast, which also included Molly Ringwald and Jeffrey Tambor, it was panned by critics and audiences alike; for example, Entertainment Weekly said it was "like Misery scripted by a witless John Hughes imitator". The film, which cost $14 million to make, sold only $8.8 million in tickets in the U.S.
Williamson developed a new TV series for The CW entitled The Vampire Diaries, which was adapted from a novel series of the same name by L.J. Smith. The series follows the life of Elena Gilbert (Nina Dobrev), who falls in love with vampire Stefan Salvatore (Paul Wesley), and soon finds herself caught in a love triangle between Stefan and his older brother, Damon (Ian Somerhalder), while the brothers are also being haunted by the past they've had with Katherine Pierce (also played by Nina Dobrev). The series also focuses on the lives of Elena's friends and other inhabitants of the fictional town of Mystic Falls, Virginia.
The Vampire Diaries premiered on September 10, 2009, to a successful run that netted the series a full-season pickup on October 21, 2009, and was later renewed for a second season. On April 26th, 2011 it was renewed for a third season.
In 2001, Williamson created a mid-season replacement for The WB called "Glory Days", set in a coastal community in Washington state, where very weird things were happening—shades of "Twin Peaks", it seemed. It debuted in January 2002, but only ten episodes were produced.
Williamson penned another script for Wes Craven, Cursed, which was released in 2005 and starred Christina Ricci, Jesse Eisenberg, Joshua Jackson, and Shannon Elizabeth. The film suffered many script and scheduling difficulties during production and ultimately failed to perform at the box office.
2005 saw the release of his newest horror film, Venom, about a group of teens stalked by a crazed killer in the bayous of Louisiana. Williamson is listed as a producer of the film, but not as a writer.
Williamson wrote and produced "Hidden Palms" for The CW. It was a coming-of-age drama about a troubled teen who moves with his mother and new stepfather to the gated community of Palm Springs where he uncovers some dark secrets. "Palms" was originally intended to be a midseason replacement set to air in March but "Pussycat Dolls Present: The Search for the Next Doll" aired in its timeslot instead. The pilot eventually premiered on May 30, 2007. Eight episodes were ordered by the network but due to low ratings the series was canceled. The final episode aired on July 4, 2007.
Williamson wrote the script for Scream 4 and is tapped to write the storybook for Scream 5.