Busch's 2011 Sprint Cup Series season began with a wreck in the Budweiser Shootout at Daytona International Speedway. Busch also raced in all three NASCAR points events at Daytona, with a best finish of fifth in the Truck Series event; the next week at Phoenix, Busch dominated the Truck Series race, and led every lap of the race in the Nationwide Series Bashas' Supermarkets 200. He was close to sweep all 3 races at Phoenix again, but Jeff Gordon overtook him with 9 laps to go and took the trophy. Busch swept the March weekend at Bristol, his second sweep of a Bristol weekend. On April 30, 2011, Busch won his third straight spring race at Richmond International Raceway, capturing his second win of the 2011 season.
Following an on-track incident with Kevin Harvick during the Southern 500 on May 7, 2011, and a post-race scuffle that saw Busch push Harvick's unoccupied car on pit road with his car, Busch and Harvick were fined $25,000 and put on probation for four races, in addition to the Sprint All-Star Race. Following the Truck Series O'Reilly Auto Parts 250 at Kansas Speedway, Busch became involved in an altercation with Richard Childress; Busch had bumped Childress' No. 22 truck, driven by Joey Coulter, on the race's cooldown lap, and according to witnesses about 30 minutes after the race Childress came up to Busch, put him in a head lock and started punching him. Childress had previously stated, following Busch's altercation with Harvick at Darlington, that he would consider it personal if Busch damaged another vehicle he owned; Childress was fined $150,000 for the incident, and placed on probation for the remainder of the year. Busch stated that the bump had been congratulatory, and that had he realised the resulting damage would upset Childress he would have paid for the repairs.
Busch won the inaugural Sprint Cup race at Kentucky Speedway on July 9, 2011 beating David Reutimann and Jimmie Johnson; at Watkins Glen in August, Busch led the most laps but lost the lead to Marcos Ambrose during a green-white-checkered finish. The following week Busch won the Pure Michigan 400 at Michigan International Speedway, becoming the first driver that season to clinch a spot in the Chase for the Sprint Cup.
On August 24, 2011, while competing in the Truck Series O'Reilly 200 at Bristol Motor Speedway, Busch was hit by the Joe Denette Motorsports truck of Elliott Sadler, sending him into the wall and causing severe damage to his truck, while waiting for the caution flag to be displayed, Busch drove rapidly around the track and hit Sadler, spinning him. Busch stated afterwards that Sadler, a regular driver for Kevin Harvick in the Nationwide Series, deliberately crashed him due to his connection with Harvick, who at the time was feuding with Busch in the Sprint Cup Series, Sadler and Harvick denied any connection, and no penalties were assessed for the incident.
On August 26, 2011, Busch won the Nationwide Series Food City 250 at Bristol Motor Speedway, surpassing Mark Martin for the most Nationwide series wins ever, with 50, and also simultaneously became the first driver to win three consecutive races at Bristol Motor Speedway in the Nationwide Series. The race also had the closest finish at Bristol in series history, 0.019 seconds over teammate Joey Logano.
On November 4, 2011, Busch was involved in an incident during the Camping World Truck Series WinStar World Casino 350K at Texas Motor Speedway. While passing the lapped truck of Johnny Chapman, Busch made contact with series regular championship contender Ron Hornaday, Jr., causing a caution flag to be displayed. While under the yellow flag, Busch drove to Hornaday's truck during the caution and deliberately turned him into the outside wall, smashing Hornaday's truck and ending Hornaday's title hopes. NASCAR immediately black-flagged Busch and parked him for the remainder of the race for his aggressive driving; this was the first case of this being done since Robby Gordon was parked in a 2007 Nationwide Series race at Circuit Gilles Villeneuve. Busch declined comment after speaking with NASCAR officials, Hornaday stated "I'll be at his house Monday morning" if Busch was not suspended.
On November 7, 2011, NASCAR fined Busch $50,000 for "actions detrimental to stock car racing", in addition, Busch was placed on probation for the rest of the year, being warned that he would be suspended indefinitely if he committed another offense detrimental to stock car racing or disrupted the orderly conduct of a NASCAR event during the remainder of the 2011 season.
On November 10, 2011, it was reported that M&M's, the primary sponsor for Busch's Sprint Cup team, refused to sponsor the 18 for the last few races as a result of Busch's behavior in Texas. Aric Almirola was briefly considered by Joe Gibbs Racing to replace Busch for the remainder of the year, while it was decided by the team to allow Busch to drive in the final two races of the season with Interstate Batteries sponsorship, Busch was replaced in the team's Nationwide Series car for the final race of the year at Homestead-Miami Speedway by the request of the team's sponsor, Z-Line Designs. Busch was subsequently replaced by Denny Hamlin as had occurred previously at Texas.
On July 10, 2011, Busch won the 32nd annual Slinger Nationals at Slinger Speedway in Wisconsin. Two weeks later, Busch won the 38th annual TD Bank 250 presented by New England Dodge Dealers at Oxford Plains Speedway; it was his third attempt to win the event. Kyle Busch became only the second active NASCAR Sprint Cup Series driver to win the event, New England's largest short track race, joining Kevin Harvick as the only other active Sprint Cup driver to win the race with his victory in 2008. Busch stated "I've had this one on my list of big races that I wanted to win and now that I've done it, it feels great - it was everything I thought it would be." Busch also won the preliminary Pro All Star Series Oxford 150 the previous night, sweeping the weekend's events.
On May 24, 2011, Busch was cited for reckless driving and speeding near Troutman, North Carolina, driving 128 mph (206 km/h) in a 45 mph (72 km/h) speed limit zone. He issued a public apology in which he stated he got "carried away" test driving a Lexus LFA. On August 23, 2011, he received a $1,000 fine and had his license suspended for 45 days after he pleaded guilty to speeding. He was also ordered to serve 30 hours of community service and placed on one year of unsupervised probation. On April 29, 2014, Busch was cited for traveling 60 mph (97 km/h) in a 45 mph (72 km/h) speed limit zone on NC 73 in Denver, North Carolina. Busch claimed he thought the speed limit was 55 mph (89 km/h). The officer claimed Busch had a "disrespectful attitude."