Kardashian was born on October 21, 1980 in Los Angeles, California, the daughter of Robert and Kris (nee Houghton). She has an older sister, Kourtney, a younger sister, Khloe, and a younger brother, Rob. Their mother is of Dutch, English, Irish, and Scottish ancestry, while their father was a third-generation Armenian-American. After their parents divorced in 1991, her mother married again that year, to Caitlyn Jenner (then Bruce), the 1976 Summer Olympics decathlon winner.

In February 2007, a sex tape made by Kardashian and Ray J in 2003 was leaked. Kardashian filed a lawsuit against Vivid Entertainment, who distributed the film as Kim K Superstar. She later dropped the suit and settled for a reported US$5 million. In October 2007 Kardashian, in addition to her mother Kris Jenner, her step-parent Caitlyn Jenner (Bruce), her siblings Kourtney, Khloe, and Rob Kardashian, and half-sisters Kendall and Kylie Jenner, began to appear in the reality television series Keeping Up with the Kardashians. The series proved successful for E!, and has led to the creations of spin-offs including Kourtney and Kim Take New York and Kourtney and Kim Take Miami. In one of the episodes, Kim discussed an offer from Playboy to appear nude in the magazine. That December, Kardashian posed for a nude pictorial for Playboy.  In 2008, she made her feature film debut in the disaster film spoof Disaster Movie, in which she appeared as a character named Lisa. That same year, she was a participant on season seven of Dancing with the Stars, where she was partnered with Mark Ballas. Kardashian was the third contestant to be eliminated. In January 2009, Kardashian made a cameo appearance during an episode of the sitcom How I Met Your Mother, in the episode "Benefits". In April, she released a workout DVD series through her television production company Kimsaprincess Productions, LLC which has seen the release of three successful workout videos, Fit in Your Jeans by Friday, with trainers Jennifer Galardi and Patrick Goudeau. Kardashian played Elle in four episodes of the television series Beyond the Break.  Kardashian become a guest host of WrestleMania XXIV and guest judge on America's Next Top Model in August of that year. In September, Fusion Beauty and Seven Bar Foundation launched "Kiss Away Poverty", with Kardashian as the face of the campaign. For every LipFusion lipgloss sold, US$1 went to the Foundation to fund women entrepreneurs in the US. The following month, she released her first fragrance self-titled "Kim Kardashian". In December 2009, Kardashian made a guest star appearance on CBS's CSI: NY with Vanessa Minnillo.

Why was KUWTK considered to be a breakthrough with reality tv?