Busch was born to Thomas and Gaye Busch in Las Vegas, Nevada. At the age of six, Busch was accompanying his father to the track and driving go-carts himself. As an underage teenager, he competed in Dwarf competition winning in just his second race, at the Las Vegas Speedway Park.
This father and son team competed western tracks from Southern California to Utah. In 1994, his first full year as a driver, Busch won ten consecutive races at ten different tracks.
His father eventually sold their dwarf equipment and purchased a powerful car for the Legends Series, which Busch began driving in 1996 at age 18. After graduating at Durango High School, Busch enrolled at the University of Arizona, hoping to earn a degree in Pharmacy.
Busch became engaged to girlfriend Eva Bryan while attending the 2005 Hungarian Grand Prix. On July 27, 2006, three years to the day of them meeting on a blind date, they were married in Virginia. The footage was taped and later aired on national television. Busch announced on June 30, 2011, "Those in the NASCAR community have been aware for some time now that we are no longer together and we are legally separated".
The announcement came days after Busch kissed another woman in Victory Lane celebration following a win at Sonoma Raceway. Busch and Eva Bryan filed for divorce in early June and were legally separated later that month.
Busch has a documented history of verbally abusing members of his team and the media. Busch revealed that he has been working with a sports psychologist for two months, to work on "personal issues" according to interviews during the 2011 NASCAR Championship week.
Busch is also an avid baseball fan and stated the goal of visiting every ballpark nationwide. His favorite baseball team is the Chicago Cubs.
His younger brother Kyle Busch also competes full-time in the Sprint Cup Series champion and runs part-time in both the Xfinity Series and Camping World Truck Series.
On November 12, 2008, DEI and Felix Sabates' Chip Ganassi Racing (Dodge) merged their NASCAR operations into one organisation. The team, which became Earnhardt Ganssi Racing, remained a Chevy team The #42 team joined the #1 and #8. In 2014, EGR reverted to the Chip Ganassi Racing name.