Kourtney was born in Los Angeles, California to Robert Kardashian and Kris Jenner. She is the eldest of four children from Bob and Kris. After her parents divorce, she spent her time between her father's and mother's houses in Beverly Hills. Her mother married Bruce Jenner, 1976 Olympic Gold Metal Champion for the Decathlon and later had two children with him. After the O.J. Simpson murder trial propelled Kourtney's father, Bob, into the spotlight (he was a member of the Dream Team of lawyers defending the accused murderer in what journalists hail the Trial of the Century), her mother decided it would be safer to move her family to Hidden Hills, California.

Kourtney attended Marymount High School in Los Angeles, an all-girls private Catholic high school. After graduation, she enrolled at Southern Methodist University in Dallas, Texas. After two years, she transferred to the University of Arizona in Tucson, Arizona. She graduated in May of 2002 with a Bachelor's Degree in Theatre Arts with a minor in Spanish. After graduation, she and her mother opened up children's clothing boutiques in both the Los Angeles Area (818) and New York City, called Smooch, which carries the brand Crib Rock Couture. She is now, at the age of 26, starring in a reality television show called Filthy Rich: Cattle Drive (2005) that will earn money for charity.