Her most recognized roles are Carmen Ibanez in Starship Troopers (1997), Kelly Van Ryan in Wild Things (1998) and Bond girl Christmas Jones in The World Is Not Enough (1999). She has also appeared in films Drop Dead Gorgeous (1999), Valentine (2001), Undercover Brother (2002), Scary Movie 3 (2003), Love Actually (2003), and Madea's Witness Protection (2012).

Her television roles include Paramount Network's sitcom Blue Mountain State (2010–2011), ABC Family's mystery-thriller series Twisted (2013–2014) and CBS' soap opera The Bold and the Beautiful (2019–present). Richards starred on the E! reality show Denise Richards: It's Complicated (2008–2009) and Bravo's reality television series The Real Housewives of Beverly Hills (2019–2020). In 2011, Richards published a memoir, The Real Girl Next Door, which became a New York Times Best Seller.