Shelton, who considered her prolific work in TV-movies valuable experience, ("Movies of the Week are like mini-features") counted among her TV credits a 1994 appearance in the syndicated "Hercules in the Underworld", significant as it marked an early starring adult acting job, in addition to a host of dramatic NBC productions. In 1995, her feature career took off with a supporting role in Oliver Stone's "Nixon" biopic. Shelton played the president's teenage daughter Tricia in a fairly high-profile role that would garner her attention. She followed up with a part in the less prestigious children's actioner "Warriors of Virtue" in 1997, and scored a featured part in "Pleasantville" the following year. She portrayed Margaret in the acclaimed film, the TV land girl who captures the heart of Tobey Maguire's thoughtful David. The role landed Shelton on the film's theatrical poster, with her character playing a crucial part in one of the feature's most memorable and visually arresting sequences. In 1999, she joined in film's teen boom, playing one of the popular high school girls in the romantic comedy "Never Been Kissed" and lensing her first feature starring role as a young cheerleader who becomes pregnant and is aided by her loyal squad in a bank robbery so that her child will be provided for in "Sugar and Spice". Also in 1999, Shelton impressed as an enchanting supporting player in the comedy "The Bachelor", playing the sardonic younger sister of a woman (Renee Zellweger) whose boyfriend (Chris O'Donnell) seems unwilling to commit.
Shelton has additionally been featured in the films "Lured Innocence" (starring Dennis Hopper and Talia Shire, 1999) and "Bubble Boy" (alongside Jake Gyllenhaal), released in 2001. In 2002, Shelton appeared in the romantic comedy "Just a Kiss," about a group of 30-somethings looking for a way to deal with their infidelity. She next acted alongside her sister in the film "Moving Allan" (AKA "Between Us," lensed 2001), a dark comedy directed by their father Christopher Shelton, best known for helming many TV commercials. Tapped by executive producer Fisher Stevens, who directed her in "Just a Kiss," Shelton played the best friend to a hard-partying socialite (Brittany Murphy) in the 2003 comedy "Uptown Girls."
The actress had a brief but memorable turn in director Robert Rodriguez and writer-artist Frank Miller's visually arresting adaptation of Miller's crime noir comic book series "Sin City" (2005). Shelton played the beautiful crimson-gowned, crimson-lipped Customer in the opening sequence based on Miller's graphic short "The Babe Wore Red"--the actress and Josh Hartnett agreed to appear as a favor to Rodriguez, who directed the piece as a short film to win the approval of Miller to move forward on the subsequent feature.