Dale Jr. cut his teeth racing around the southeast in Late Model stock cars with his brother, Kerry, and sister, Kelley. Much of Dale Jr.'s early racing was done at Myrtle Beach Speedway each weekend after working on his car during the week. Dale Jr. also competed at Concord Speedway, North Wilkesboro Speedway and South Boston Speedway among other tracks with the support of long-time Earnhardt partners Mom 'n' Pops and Sun Drop.

Dale Earnhardt Sr. pulled a chassis from the stash used during Jeff Green's Dale Earnhardt Inc. (DEI) tenure to give his 21-year-old son a shot at NASCAR Xfinity Series competition. But he did it under one condition – Dale Jr. had to do the work. With the help of his friend, Wesley Sherrill, Dale got his shot at Myrtle Beach Speedway, a track he was very familiar with from four years of late model competition. Dale Jr. competed in the late model race at Myrtle Beach on the same day of his Xfinity Series debut. His introduction to NASCAR was successful, as he qualified the No. 31 Mom 'n' Pop's Chevrolet seventh and finished 14th. Following the race his uncle, Danny Earnhardt, called Dale Sr. and reported with confidence and conviction, "The boy can drive."

The plan in 1997 was to enter Dale in seven races to continue his progression and determine if he was cut out for NASCAR Xfinity Series competition. He finished seventh in the Aug. 16, 1997 at Michigan to earn his first career NASCAR top 10. He was not to race again until Charlotte some six weeks later, but Dale Sr. received a call from team owner Ed Whitaker asking if Junior could drive his No. 7 Chevrolet at Bristol and Fontana. With Tony Eury Sr. as his crew chief, Dale Jr. qualified second at Bristol in Whitaker's No. 7 Church Brothers Chevrolet and led 22 laps. Five weeks later at Fontana, Junior started 11th but handling issues forced an early exit en route to a 34th-place finish. Junior ended the year competing in a total of eight races, not nine, as a practice crash at Charlotte damaging his only race car and preventing him from racing that weekend.

On April 4, 1998: During the seventh race of the season at Texas Motor Speedway. Dale started 16th, overcame contact with another car, an unscheduled pit stop, and a back-of-the-pack restart to find himself in the top 10 as the laps winded down. With Joe Nemechek leading and Elliott Sadler second, Tony Eury Sr. called his driver to pit road under caution for four fresh tires. Dale restarted in sixth with six laps to go. He made quick work of all the cars in front of him, caught the leader, and found his opportunity to overtake him coming off Turn 4 as the white flag waved. Sadler, too, came charging to the front, setting up a last-lap duel that resulted in Earnhardt Jr. edging Sadler by .178 seconds to the finish line. After averaging only one win every 53 starts in the late model ranks, Dale Jr. had just won his first XFINITY Series race in his 16th start.

After a career-defining win at Texas in only the seventh race of the 1998 season, the floodgates opened. Dale Jr. proceeded to drive the No. 3 AC Delco Chevrolet to seven victories, 16 top-fives, 22 top-10s, and three poles to give his father's company, Dale Earnhardt Inc., its first championship. Dale’s wins came at Texas, Dover, Milwaukee, Fontana, Indianapolis Raceway Park, Richmond, and Gateway. Of his 6,055 laps completed in '98, Junior led 1,615 of them. The title hunt was a two-horse race between Earnhardt Jr. and Matt Kenseth. Kenseth had only three wins to Junior's seven but boasted more top fives and top 10s. In the end, Dale Jr. beat Kenseth by a mere 48 points.

With Budweiser signed on to sponsor Dale's plunge into the Cup Series in 2000, the grand debut came via a partial five-race schedule in 1999 that started at Charlotte Motor Speedway. Dale's attempt to qualify for the 1999 Coca-Cola 600 was dubbed "Countdown To E Day", as the world anticipated the arrival of the next generation Earnhardt into stock car racing's biggest series.

Dale Jr. went through the first 14 events of the 1999 season winless. It wasn't until Dover on June 5, 1999, that Dale broke through and scored his first win of the year. It ignited a three-week tear in which he followed suit with victories at South Boston and Watkins Glen, his first road-course win. The momentum of a mid-season surge led to six victories total in '99 to go with 18 top-fives and 22 top-10s. Dale completed more laps than the previous year (6,231 to 6,055). Ultimately, it was enough to outlast Jeff Green (-280) and Matt Kenseth (-320) in the points race.

With Budweiser as his primary sponsor, Dale Jr. moved into NASCAR Cup Series action full-time in 2000. Tony Eury Sr. and the XFINITY Series championship-winning team from the previous two seasons moved with him. Dale’s official rookie season featured highs and lows. He captured two wins in his first 16 races and became the first rookie to win NASCAR's all-star race, The Winston.

In April 2000 during his 12th career Cup start, Dale Jr. found victory lane at Texas Motor Speedway by leading 108 of 334 laps in his No. 8 Budweiser Chevrolet Monte Carlo and crossing the finish line 5.9 seconds ahead of second-place finisher Jeff Burton.

No rookie had ever won NASCAR's All-Star race, but Dale Jr. was no ordinary rookie. Having already won two races (Texas and Richmond) in his first 16 races, Dale was entering All-Star week with momentum, so much so that Charlotte Motor Speedway promoter Humpy Wheeler picked the Budweiser team to shock the world and win The Winston. The race was divided into three segments (30 laps, 30 laps, 10 laps). Junior finished third in each of the first two segments. He then was part of a gut-wrenching decision to make a pit stop with eight laps to go in the final segment for four new tires. The call for fresh rubber relegated the No. 8 Chevrolet to 10th for the restart. Passing cars every lap, Dale Jr. charged to the front. He inched behind leader Dale Jarrett with two laps to go and nosed ahead with the white flag waving. He then pulled away, or as TNT broadcaster Eli Gold described it, "He kicked those Clydesdales into high gear!

Dale teamed up with his father, Andy Pilgrim, and Kelly Collins to drive a Chevrolet Corvette in the 2001 Rolex 24 at Daytona. The group finished fourth overall and second in class in what was Dale’s first and only sports car race to date.

Long considered one of NASCAR's most memorable moments, Dale scored an emotional victory in the first race at Daytona since the tragic loss of Dale Earnhardt Sr. Driving a special No. 8 Budweiser/Major League Baseball All-Star paint scheme, Dale dominated by leading 116 of 160 laps but found himself in sixth place on the final restart with six laps to go. The Bud driver needed only two laps to blow past five cars in front of him, and he held off teammate Michael Waltrip to take the checkered flag and score the popular victory.

On April 6, 2003, Dale capped an astounding string of victories by winning his fourth consecutive race at Talladega Superspeedway, a stretch that reached back to Oct. 21, 2001. His four wins set a record for most consecutive victories at Talladega.

Dale Jr. etched his name with NASCAR's all-time greats by winning the event affectionately known as "The Great American Race" – the Daytona 500. Driving a special Budweiser "Born-On Dating" paint scheme, Junior had the final word in a day-long bout with Tony Stewart by making a pass with no drafting help with 19 laps to go. He held onto the top spot with Stewart close behind and earned the popular victory on stock car racing's biggest stage.

Dale Jr. entered the fall weekend at Bristol Motor Speedway prepared for double duty, as he was tabbed to drive the No. 81 Menards Chevrolet for DEI in the Food City 250 and the No. 8 Budweiser Chevrolet in the Cup race the following night. Paired up with DEI crew chief Pete Rondeau for the first time, Junior started from the pole in the Friday night race and led 125 laps. The race was prolonged for a green-white-checkered finish, which Dale mastered perfectly to beat Matt Kenseth to the stripe. It gave Junior two XFINITY Series victories in four races in 2004. The following evening provided even more fireworks. Dale led a career-high 295 of 500 laps and added "Bristol night race" to his resume. He did it despite qualifying a season-worst 30th. Savvy pit strategy helped him gain track position, and he engaged in an epic battle with Rusty Wallace for the race lead. In third place on a lap 399 restart, the Bud driver needed only 18 laps to pass Jeff Burton and Ryan Newman to regain a lead he would never relinquish.

In June 2007, Dale Jr. opened a new chapter of his racing career by making a highly-publicized move to Hendrick Motorsports. Junior announced his decision in front of a crowded room of media and onlookers on June 13, 2007. In his opening remarks, Dale thanked the fans for their patience and explained his thought process in making his decision. He concluded with, "It is great honor to introduce you to my new boss... Mr. Rick Hendrick."

To honor his father's posthumous induction into the NASCAR Hall of Fame, Dale Jr. brought back his dad's famous No. 3 and one of his best paint schemes to a NASCAR XFINITY Series race on July 2, 2010, at Daytona International Speedway. The tribute was a joint effort by JR Motorsports, Dale Earnhardt Inc., and Richard Childress Racing, and the No. 3 Wrangler Chevrolet was unveiled at a press conference on the grounds of JR Motorsports on April 29, 2010. But with the famed yellow-and-blue scheme, Dale did more than pay tribute – he won the race, brought many to tears, and refurbished old feelings for many who cheered the No. 3 for years.

Dale Earnhardt Jr. captured his second Daytona 500 victory at Daytona International Speedway. The victory, the 20th of Earnhardt Jr.'s career, came in dramatic fashion as he fended off all challengers in the late laps en route to his first victory since June 2012.

In his 30th attempt at one of NASCAR's most historic tracks, Dale Earnhardt Jr. scored his first-ever victory at Martinsville Speedway by using the bump-and-run on Tony Stewart and outlasting teammate Jeff Gordon in a chaotic sprint to the checkered flag Sunday in the Goody's Headache Relief Shot 500. It is Earnhardt's 23rd career victory and fourth this season.

Dale Earnhardt Jr., a champion as both a competitor and team owner, has been named the recipient of the prestigious Myers Brothers Award for 2014. Earnhardt, 40, was chosen by a vote of the National Motorsports Press Association and presented the award during Thursday's annual NASCAR NMPA Myers Brothers Awards Luncheon held at the Wynn Las Vegas.

On April 25, 2017, after 18 seasons and more than 600 races behind the wheel, Dale Jr. announced that the 2017 NASCAR Cup Series season would be his last. Dale continues to race a handful of late model races every year.

In 2018, Dale joined the broadcast booth with NBC, calling the shots for NASCAR, and also integrated into the NFL, Kentucky Derby, and the Olympics. In 2025, he will join Prime Video and TNT Sports for a 10-week summer stretch of races. Kicking off during the Coke 600 in May and wrapping up at Indianapolis Motor Speedway in July.

It was announced in January 2025, that JR Motorsports would attempt to qualify for its first Cup Series event at the DAYTONA 500, a first for Dale as a team owner. The team not only qualified, but earned a top-10 finish in the 2025 DAYTONA 500.