2007–2008 McDowell made his NASCAR debut in the
Craftsman Truck Series. Driving the No. 17 for
Darrell Waltrip Motorsports, McDowell qualified 29th and finished 30th after a late wreck. McDowell moved to the
Busch Series as a
developmental driver for
Nextel Cup Series team
Michael Waltrip Racing. Driving the No. 00
Toyota, McDowell drove at
Texas,
Phoenix, and
Homestead, finishing respectively twentieth, fourteenth, and 32nd. McDowell was chosen to drive the No. 00 Cup Series car in 2008 after
Dale Jarrett's retirement;
David Reutimann replaced Jarrett in the No. 44
UPS-sponsored car. McDowell started 34th and finished 26th in his Sprint Cup debut, the
Goody's Cool Orange 500, after a flat tire near the end of the race. After the race, he was criticized by veteran driver
Jeff Burton for having blocked Burton's way to leader
Denny Hamlin near the end of the race (McDowell was racing for the
Lucky Dog free pass, which Burton did not realize at the time of his comments). In early August 2008, McDowell was pulled from the No. 00
Toyota Camry Sprint Cup car in favor of veteran NASCAR driver
Mike Skinner for three races. Skinner helped evaluate the team's progress while trying to get the No. 00 into the Top 35 in owner points, though McDowell returned to the ride at Richmond on September 6, 2008. McDowell was again pulled from the No. 00 Toyota Camry when he failed to qualify for the
Camping World RV 400 at
Kansas on September 28. McDowell's contract was not renewed by MWR for 2009 when
Michael Waltrip decided not to retire, and the team did not have a sponsorship for another car.
Crash at Texas Motor Speedway While performing a qualifying attempt for the
2008 Samsung 500 at
Texas Motor Speedway on April 4, 2008, McDowell had an accident that was strikingly similar to that of another racer with a road-racing background,
Gordon Smiley, who died in a crash during
Indianapolis 500 time trials in 1982. McDowell's right front
sway bar broke entering Turn 1, which caused the car to hit the
SAFER barrier almost head-on at approximately , according to data obtained and reported by
SPEED channel (185 mph to zero mph in one foot, as reported by SPEED's
Bob Dillner, before accelerating in the other direction). The car spun around once while tipping onto its roof, and then barrel-rolled eight times with fire coming out of the engine compartment, shedding debris in all directions, until coming to a stop back onto its tires. A large, dark impact mark was seen on the SAFER barrier, which showed how hard the car hit the barrier, which had to be repaired (the barrier moved inward when the car hit it), and as a result, qualifying for the race was delayed by an hour. The safety features of the barrier, the
HANS device and the
Car of Tomorrow racecar protected him. It formed a partnership with
Whitney Motorsports and
Mike Curb to field McDowell's car, which carried the No. 98. In the
2013 Daytona 500, McDowell recorded a then-career high ninth-place finish. Later in the season in the
Nationwide Series, McDowell won the pole for the inaugural
Nationwide Children's Hospital 200 at
Mid-Ohio. McDowell finished second behind
A. J. Allmendinger.
2014: Leavine Family Racing In October 2013, it was announced that McDowell would be moving to
Leavine Family Racing's No. 95 Ford for the
2014 NASCAR Sprint Cup Series season. McDowell failed to qualify for the
2014 Daytona 500. McDowell had a Sprint Cup career-best seventh place finish in the
Coke Zero 400. At the
Cheez-It 355 at The Glen, on lap 64,
Greg Biffle came up on
Ryan Newman's front bumper, turning him into the outside retaining wall. His car ricocheted off the wall into McDowell's path, where Newman barely clipped McDowell in the right rear of his car, and with the force of the impact, the rear end housing snapped, causing him to get airborne. The car bounced twice in the air before it hit the wall. His housing was forced against the wall. The race was red-flagged, though both drivers were unharmed.
2015–2016 ] McDowell returned to the LFR No. 95 car for a twenty race schedule in 2015. The team merged with
Circle Sport in 2016 and switched to
Chevrolet, with McDowell splitting the schedule with
Ty Dillon with sponsorship from
Thrivent Financial,
Cheerios, and WRL Contractors among others. The season started with McDowell placing 15th in the 2016 Daytona 500, a best for LFR in the Great American Race. McDowell was able to get a tenth place finish in the
2016 Coke Zero 400, his best finish of the season. At the end of the season at
Homestead, McDowell drove the No. 59 Chevrolet after CSLFR purchased a charter from the closing
Tommy Baldwin Racing. McDowell ran decent all night, and towards the end, he was able to avoid the big wreck involving Championship contender
Carl Edwards and was able to get a tenth-place finish, his first non
restrictor plate top-ten finish. McDowell drove for
Richard Childress Racing in the No. 2
Rheem Chevrolet in a one-race deal at
Road America, which got McDowell his first NASCAR victory. McDowell led the final 24 laps en route to the win.
2017 in 2017 McDowell returned to Leavine Family Racing's No. 95 Chevrolet in 2017. He started the season with a fifteenth-place finish in the
Daytona 500. At
Kansas, McDowell scored a season-best thirteenth-place finish. At
Dover, McDowell scored his third straight top-twenty finish, a career first, when he finished nineteenth upon avoiding a last-lap crash. At Daytona for the
Coke Zero 400, McDowell spent most of the race towards the front and competed late for the win, as he was in second place on the last lap before ending the race with a career-best fourth-place finish, his first career top-five finish. It was also the best finishing result for Leavine Family Racing as a team. McDowell completed 99 percent of the laps in 2017, the most among any full-time driver in the Cup Series that season, and finished a career-best 26th in the standings. It would be his final season with LFR.
2018: Front Row Motorsports On September 19, 2017, Leavine announced
Kasey Kahne would be replacing McDowell in the No. 95 car for the 2018 season. On November 24, 2017,
Front Row Motorsports announced that McDowell would drive their No. 34 car full-time in
2018, replacing
Landon Cassill. In the first race of the season, McDowell raced up front late and finished ninth in the
2018 Daytona 500, his fifth straight top-fifteen finish at Daytona (and third top ten in the last four races at the track) and tied his career-best finish in the race. McDowell would have a strong run in the 2018 Coke Zero Sugar 400, leading twenty laps, a career-best, and would finish second in stage 2 behind Ricky Stenhouse Jr. Unfortunately, with seven laps to go, McDowell would crash out of the race and finish 26th. McDowell would later tie his best finish in the Cup series points standings of 26th after leading laps at his final race of the season in Homestead.
2019 In 2019, McDowell returned to the No. 34 car for Front Row Motorsports. McDowell's longtime sponsor
K-Love took a year-long break from being a primary sponsor of his car. In the
2019 Daytona 500, the first race of the season, he qualified in 34th and finished in fifth, which would become his career-best finish in the Daytona 500 as well as his second-best finish in a Cup Series race. After the race, 2018 champion
Joey Logano confronted McDowell for not helping him win the Daytona 500, in which McDowell stated, "My team doesn't pay me to push you." During qualifying for the
2019 TicketGuardian 500 at
ISM Raceway, McDowell had an on-track incident with
Daniel Suárez, which resulted in a fight on pit road. Two days before the
2019 Bank of America Roval 400 at
Charlotte Motor Speedway, McDowell was rushed to the hospital after complaining of abdominal pain. He was cleared to race after passing
kidney stones during the examination. McDowell would go on to run up front in the 1000bulbs.com 500 at Talladega Superspeedway, and even had a chance to win the race being in third place on the final lap of the race, and would finish fifth, capturing his second top-five of 2019, the first time he would have multiple top-fives in a single cup series season in his career.
2020 On December 12, 2019, Front Row Motorsports announced that McDowell would return to the No. 34 for the
2020 season. McDowell started the year off with a fourteenth-place finish in the
2020 Daytona 500, his fifth consecutive top-fifteen in the Daytona 500 and his eighth top-fifteen in his last nine Daytona races. McDowell would go on to qualify 3rd for the second Charlotte race due to the random draw, and McDowell has boomed onto the scene since coming off of NASCAR's break. McDowell would capture an eighth-place finish at Pocono and, following a DNF, a seventh-place finish at Indianapolis, marking the first time in his career he earned two top-tens two weeks in a row. McDowell would set a career-best for most top-fifteens in a season in just sixteen races with six, and has finished higher than his qualifying effort in fifteen of his twenty starts. In his first twenty starts, McDowell had more lead lap finishes than the likes of
Kyle Busch,
Erik Jones,
Jimmie Johnson,
William Byron,
Alex Bowman, and
Ryan Blaney, finishing on the lead lap fifteen of the first twenty races that season. During the All-Star Open at
Bristol Motor Speedway, McDowell would win the pole and run up front most of the day before an on-track incident with driver
Bubba Wallace, which led to an angry interview from Wallace, as well as leaving the front bumper of his car by McDowell's garage. McDowell and Wallace later set aside their differences and, along with McDowell's sponsor carparts.com, used the front bumper to raise over $34,000 for multiple charities, including Victory Junction, and eventually gave away the front bumper to a fan. McDowell would capture his first top-ten finish on a road course in his career at the Daytona road course and would earn his new best career points standings finish in the Cup Series in 23rd. It was announced a month before the 2021 season started that McDowell had signed a one-year contract extension with FRM to return to the No. 34 for the following season.
2021: Daytona 500 win and first playoff appearance McDowell remained in FRM's No. 34 for a fourth year in
2021. He won the season-opening
Daytona 500 after avoiding a crash involving the leaders
Joey Logano and
Brad Keselowski on the final lap. Before his big victory, McDowell had the second-most Cup Series starts before his first win. It was his first Cup Series win in his 358th start, second only to
Michael Waltrip, whose first win came in his
463rd start. He would go on to finish the first three races of the season inside the top-ten. McDowell also nearly won at Talladega in the spring, finishing a close third behind Keselowski and Byron. McDowell would follow this performance by a strong seventh place finish at the inaugural cup series race at
Circuit of the Americas after early contact with
Martin Truex Jr.. McDowell's win at Daytona locked him into the All-Star Race and the NASCAR playoffs for the first time in his fourteen-year Cup Series career. McDowell was eliminated from the playoffs following the conclusion of the Round of 16 at
Bristol. He finished the season with one win, two top-fives, five top-tens, an average finish of 20.5, and finished sixteenth in the points standings.
2023: Return to the playoffs McDowell began the
2023 season with a 28th-place finish at the
2023 Daytona 500. He dominated the
Indianapolis road race, landing him in the playoffs and earning him his second career win, as well as his first career stage win in the first stage of the race. He was eliminated at the conclusion of the Round of 16. He finished the season with one win, two top-fives, eight top-tens, an average finish of 19.0, and finished fifteenth in the point standings.
2024: First career pole and final year with FRM McDowell began the
2024 season with a 36th-place finish at the
2024 Daytona 500. McDowell had his first pole at Atlanta after 467 Cup Series starts. At the race at
Talladega, McDowell was leading on the final lap when he spun out trying to block
Brad Keselowski. He finished 31st, not crossing the start-finish line and being marked with a DNF. On May 8, 2024, McDowell announced he would leave FRM at the end of the 2024 season, and he had signed a multi-year contract with
Spire Motorsports to drive the No. 71 Chevrolet starting in 2025. On June 1, 2024, McDowell won his third pole of the season for the
Enjoy Illinois 300 at
Gateway. He set a track record in Round 1 of qualifying with a 32.318s (139.241 mph) lap time. McDowell finished his final year with FRM in 23rd place in the final point standings. McDowell also finished the season with a career best six poles, the most of any driver on the season.
2025: First year at Spire Motorsports in 2025 McDowell began the
2025 season with an eleventh-place finish at the
Daytona 500. At
Las Vegas, McDowell would score his first pole of the season and Spire's first Cup Series pole. McDowell would have an up-and-down year, having many close calls.
Kaulig Racing's
Josh Williams was released by the team on July 30, McDowell would drive the No. 11 for the team at
Watkins Glen in his place. On January 29, it was announced that McDowell would return to the Truck Series after sixteen years, driving the No. 07 truck for Spire Motorsports at
Daytona and
Atlanta. ==Personal life==