In 2003, Richie and best friend Paris Hilton starred in Season 1 of the reality series The Simple Life, in which they lived for a month with a family in the rural community of Altus, Arkansas. The series debuted on FOX on December 2, 2003, to high ratings. The premiere episode drew 13 million viewers, increasing FOX's Adults 18-49 rating to 79%. In Season 2, The Simple Life 2: Road Trip, the girls traveled the South driving a pink pick-up and living in a trailer. The girls had no money, credit cards or cell phones and were required to work various jobs during their trip to earn money. Their jobs included farm workers, mermaids in an underwater show, hotel maids, sausage makers, crawfishers, working for a baseball team, working in a beauty salon, Deputy Sheriffs, and working on a cattle ranch. The girls also stayed with different families or in trailer parks and on one occasion, a nude resort.

In Season 3, The Simple Life 3: Interns, the girls traveled the East Coast on a bus, staying at 15 different families' houses. Unlike Season 2, the girls did not have a swanky home on wheels and instead were traveling around the north-east in a regular Greyhound bus that was also ferrying normal members of the public that were traveling to the same destination. In late 2005, FOX chose not to renew The Simple Life, explaining that they didn't see a place for it in their schedule. A month later, cable network E! picked up the series for its fourth season. The Simple Life 4: 'Til Death Do Us Part, followed the girls as they traveled around California, acting as wife and mother to various families, though both would do tasks separately and not be seen together on screen.

The Simple Life 5: The Simple Life Goes To Camp, debuted on E! on May 28, 2007, with Hilton and Richie reconciling on Richie's birthday in the season opener. For Season 5, Hilton and Richie worked as counselors at Camp Shawnee. The camp was host to five different specialty groups: Wellness Camp, Pageant Camp, Couples Camp, Survival Camp and Drama Camp, with two episodes focused on each specialty group.

Although Season 4 was a hit for E!, drawing nearly one million viewers per episode, Season 5 saw a sharp decline in ratings. While the premiere episode and ones that followed during this season drew about the same viewership, by the 7th episode the ratings had declined to around 700,000 viewers. It was announced on July 30, 2007 that the show would not be renewed for a sixth season. In 2005, Richie made her acting debut in the comedic drama Kids in America. Richie has guest starred in television series including Eve, Six Feet Under and American Dreams, and Chuck. In July 2008, plans were announced to turn Richie's 2005 novel, The Truth About Diamonds, into a television series.

• "Chuck" .... Heather Chandler (1 episode, 2008)
       - Chuck Versus the Cougars (2008) TV episode .... Heather Chandler
• Kids in America (2005) (as Nicole Camille Richie) .... Kelly Stepford
• "8 Simple Rules... for Dating My Teenage Daughter" .... Ashley (1 episode, 2005)
  ... aka 8 Simple Rules (USA: new title)
       - Ditch Day (2005) TV episode .... Ashley
• "American Dreams" .... Brenda Reid (1 episode, 2004)
  ... aka Our Generation (Australia) (USA: working title)
       - Charade (2004) TV episode .... Brenda Reid
• "Rock Me, Baby" .... Amanda (1 episode, 2004)
       - Kiss and Don't Tell (2004) TV episode .... Amanda
• "Eve" .... Karen (1 episode, 2004)
       - Valentine's Day Reloaded (2004) TV episode .... Karen