Busch began his racing career at age 14 in a Dwarf car at Pahrump Valley Speedway,[2] introduced to the sport by his father.

[4] Busch's big break came under unfortunate circumstances when Chris Trickle, a promising driver, was critically injured in an unsolved shooting and later passed away.

He gained national attention in the 1997 Winter Heat Series at Tucson Speedway, competing against notable drivers like Ron Hornaday Jr., Matt Crafton, Greg Biffle, and Kevin Harvick.

99 Ford F-150,[2] Busch achieved four victories, finished second in the championship standings to teammate Greg Biffle, and was named Rookie of the Year.

Later that year, Roush Racing secured a multi-year deal with Rubbermaid, with its Sharpie marker brand becoming Busch's primary sponsor.

Busch secured his best finish of the season with a third-place result at the spring Talladega race, just three weeks after earning his first career Top 5 at Texas (fourth).

Busch wrapped up the season with a 21st-place finish at the postponed race in New Hampshire, ending 27th in points and second to Kevin Harvick in the Rookie of the Year standings.

He achieved his fourth consecutive win at Bristol by taking the Food City 500 in March, marking his third straight victory in that event.

Busch was still assured a spot due to NASCAR’s Champion’s Provisional Rule, which automatically qualifies the most recent series champion—Busch, with his 2004 title—if they're not in the top 35 of owner points.

During the Crown Royal 400 at Richmond, Busch launched a profanity-laced tirade on his in-car radio, seemingly directed at Penske technical director Tom German.

[11] Busch won the pole and dominated the race at Kansas by leading 152 laps, but a late fuel pickup issue cost him a victory, which went to his teammate Brad Keselowski.

After Keselowski was injured in a practice crash at Road Atlanta, Busch filled in for him at the Zippo 200 at Watkins Glen International, where he claimed the pole and won the race.

On October 2, he earned his first victory at Dover's Monster Mile, leading the final 43 laps after two late restarts and beating Jimmie Johnson.

Tensions peaked when he verbally attacked an ESPN cameraman and made an obscene gesture after a transmission failure during the season finale.

However, the exchange took a turn when Busch shouted expletives and physically confronted Menzer, prompting Penske team members to restrain him.

[13] At the start of the Sylvania 300 at New Hampshire Motor Speedway, Busch's team faced a delay in rolling their car to pit road due to a pre-race inspection issue.

[18] According to The Charlotte Observer, multiple sources confirmed that team owner Roger Penske made the decision after Busch's altercation at Homestead-Miami Speedway, viewing it as the final incident in a tumultuous tenure.

Notably, parallels were drawn between Busch's real-life struggles during the 2011–12 Sprint Cup offseason and Ricky Bobby's fictional fall from grace.

As a result of this outburst, NASCAR immediately suspended Busch from the Pocono race, citing a violation of its policy against public profanity.

A poor pit stop for both Busch brothers cost them the lead, and Kurt finished fifth in the final ten-lap shootout, won by Jimmie Johnson.

Back at Michigan, Busch started on the outside of the front row, led 43 laps, and finished third, moving up to ninth in the driver points standings.

[29] At Darlington, with just three laps to go and running in the top five, Busch was tapped from behind by Clint Bowyer, causing him to spin and crash head-on into a barrier.

We struggled at times to get the balance of the Haas Automation Chevrolet right, but we kind of found our spot just past the halfway point and made slight adjustments the rest of the way.

On February 20, 2015, NASCAR indefinitely suspended Busch following a Delaware family court's finding that it was "more likely than not" he had abused his ex-girlfriend, Patricia Driscoll.

On March 11, 2015, NASCAR lifted Busch's indefinite suspension after Delaware prosecutors determined there was insufficient evidence for a criminal case.

NASCAR also granted Busch a waiver, allowing him to remain eligible for the Chase if he won a race before the Richmond event in the fall.

At Auto Club, he won the pole, led 65 laps, but finished third after a last-lap pass by Brad Keselowski and Kevin Harvick.

On July 11, Kurt won the Quaker State 400 at Atlanta, holding off his brother Kyle, securing a playoff spot and their final 1-2 finish together.

After promising top-five results at Phoenix and Atlanta, Busch faced a series of setbacks, including poor finishes at COTA, Richmond, Bristol Dirt, Dover, and Darlington.

Busch drove a car originally fielded for Michel Jourdain Jr. (who later competed in NASCAR) and enjoyed the experience, though he was several seconds off the pace set by Oriol Servià.