Ragan was born in Unadilla, Georgia in December 1985, the son of former racer Ken Ragan. Ragan started his racing career in the Bandolero Series at age 12. During the following year, he managed to win twelve races and the National Championship. In 1999, he won the National Championship for the second time. In 2001, Ragan began racing in the Goody's Dash Series with Cam Strader. During the season, the two built late models for Ragan to use in 2002. In 2002, he began racing in the Legends Pro-Division for Mark Martin. At the end of the season, he finished fourth in the final point standings.
At age 18, Ragan moved to the Craftsman Truck Series (now Camping World Truck Series), as well as the Busch Series (now Xfinity Series) and the ARCA Racing Series. During his first career start in the ARCA Series, he qualified in the second position, but failed to finish the race after having tire failure. His first race in the Craftsman Truck Series was at Texas Motor Speedway, where he qualified 28th and finished in the 20th position for Fiddleback Racing. During the season, he failed to qualify for one race, and failed to finish six of the ten races he participated in. Ragan also participated in one Busch Series race at Homestead Miami Speedway, finishing 31st, after starting 36th. In the following season, he participated in Roush Racing: Driver X as the co-driver of the number 6 Roush Racing Ford F-150 in the Truck Series. After participating in 19 events in the series, he recorded one top-five, eight top-ten finishes, and earned one pole position.
Also in 2005, Ragan participated in three Busch Series events, as well as 19 ARCA Racing Series events, where he managed to win one race, and record three pole positions, eight top-five and 11 top-ten finishes. During the 2006 season, he participated in three Busch Series events, and two Nextel Cup Series (now Sprint Cup Series) events. He also participated in 19 Truck Series events, where he recorded two pole positions, one top-five and eight top-ten finishes.
For the 2007 season, Ragan moved to the Nextel Cup Series as the driver of the number 6 Roush Fenway Racing Ford Fusion. He also participated for the NASCAR Rookie of the Year standings in both Nextel Cup and Busch Series, where he managed to finish second in the Nextel Cup Series, while winning the award in the Busch Series. During the Cup season, Ragan recorded two top-five finishes, with one being in the 2007 Daytona 500, and three top-tens, finishing 23rd in the point standings. During the Busch Series season, he earned two pole positions, four top-five and nine top-ten finishes, while finishing fifth in point standings. Also in 2007, he participated in one ARCA Racing Series event, where he managed to finish in the fourth position.
In 2008, he raced in the Sprint Cup Series, the Nationwide Series, as well as in two ARCA Racing Series events. In the Cup season, he recorded six top-five and 14 top-ten finishes, while finishing 13th in the final point standings. During the Nationwide season, he managed to get seven top-fives and 21 top-ten finishes. Ragan clinched fourth in the final point standings. One year later in 2009, he participated in only the Cup Series and the Nationwide Series. During the 2009 NASCAR Sprint Cup Series season, he recorded zero top fives, two top-ten finishes and finished 27th in the point standings. However, in the 2009 NASCAR Nationwide Series season, he won two races, and earned five top-fives and 15 top-ten finishes, while finishing 18th in points.
During 2010, he only participated in the Sprint Cup Series. He recorded zero top fives, only three top-ten finishes and finished 24th in points once the season concluded. In 2011, he began the year almost winning the Daytona 500, but he got penalized for moving lanes before he crossed the line on the restart with two laps to go. On May 21, 2011, he won the Sprint Showdown at Charlotte Motor Speedway, passing Brad Keselowski with two laps to go.
He won the Coke Zero 400 on July 2, 2011 for his first career Sprint Cup win after getting a late push from teammate Matt Kenseth. He was eligible to compete in the "wild card" to get himself into the Chase for the Sprint Cup. After bad finishes a few weeks before the final race before the Chase at Richmond, he finished 4th but was 54 points away from 13th to put himself into a Chase position. At the end of the 2011 season UPS, Ragan's primary sponsor on the Roush Fenway Racing No. 6 Ford, announced that they would no longer sponsor the No. 6 and that the company would scale back its racing program next season, leaving the number 6 team without sponsorship and ultimately forced the camp to shut down, making Roush Fenway Racing a 3-car team for the 2012 season.
In January 2012, Ragan signed with Front Row Motorsports to drive the No. 34 Ford for the team in 2012. He drove for GC Motorsports International in the season-opening Nationwide Series event at Daytona. Ragan got off to a bad start with FRM, crashing out on lap 2 of the Daytona 500 and finishing last. He would eventually go on to finish 28th in Cup Series points.
Ragan started the 2013 season with a rotating roster of sponsors. He started the season wrecked at the Daytona 500 (along with his two other teammates, David Gilliland and Josh Wise) and had no finish better than 20th in the first nine races. However, during the Aaron's 499, Ragan started the green–white–checker restart in 10th-place. On the last lap, teammate Gilliland was able to help push him past Jimmie Johnson, Matt Kenseth, and Carl Edwards to win the race. This was his first win with Front Row Motorsports and the team's first Sprint Cup win, as well as the first NASCAR win for his sponsor for that race, Farm Rich. The 34 team improved more in 2013 earning sixteen top-25 finishes including the win, a 12th-place finish at the Irwin Tools Night Race at Bristol Motor Speedway, and a sixth-place finish at the fall Talladega race. However, three consecutive engine failures during the Chase dropped Ragan to 28th in points.
For 2014, Ragan returned to the Front Row Motorsports No. 34 to run the full season with sponsorship from Farm Rich and CSX. In the Nationwide Series, Ragan joined Biagi-DenBeste Racing in the No. 98 Ford for several races throughout the season. Ragan got his first top-10 finish on a non-restrictor plate track with Front Row Motorsports in the 2014 Goody's Headache Relief Shot 500 at Martinsville Speedway by gambling on track position with 5 laps to go in the race. It was his first top-10 of the season and came with a paint scheme paying tribute to the late Wendell Scott, who had also driven the number 34. Ragan finished 32nd in points.
Ragan returned to Front Row Motorsports in 2015. Ragan's owner points were given to new teammate Cole Whitt, but Ragan raced his way into the Daytona 500, finishing 17th in the race.
Joe Gibbs Racing
After the 500, Ragan was tapped by Joe Gibbs Racing to take over the No. 18 Toyota for several races while Kyle Busch was out with leg injuries.
At Atlanta, Ragan nursed the No. 18 to an 18th-place finish. This was followed by a 22nd-place finish at Las Vegas and 21st-place finish at Phoenix. At Auto Club, he made moves on several late restarts to take a 15th-place finish. At Martinsville, Ragan took his best finish of his stint with JGR with a fifth-place run. This was followed by a 13th-place finish at Texas.
At Bristol, Ragan started in 11th-place. However, he was caught up in a crash on lap 312 and finished 41st, 76 laps down. At Richmond, he started 10th and finished 23rd, two laps off the lead lap.
At Talladega, Ragan started in ninth place. However, he sustained severe damage in the Big One on lap 47 and finished 38th, 65 laps down.
The nine races in which Ragan participated entitled him to a one-fourth share (nine races) of Sprint Cup championship team bonuses, as the No. 18 team won the 2015 championship, worth $1,197,075 for his championship efforts.
With Erik Jones replacing Kyle Busch for the July Xfinity race at Daytona, Ragan drove the No. 20 Interstate Batteries Toyota and was running well until he was caught in an accident late in the race.
Michael Waltrip Racing
Ragan was originally scheduled to return to Front Row after his stint at JGR was over. However, it was announced on April 28 that beginning at Kansas, the No. 18 would be handed to rookie Erik Jones until Busch's return, while Ragan would move to Michael Waltrip Racing and drive their No. 55 car for the remainder of the season, beginning at Kansas.
At Kansas, Ragan was involved in a two-car accident on lap 121 with Josh Wise and finished 33rd, four laps down. At the Coca-Cola 600, he started seventh and was running well until his engine blew up with 47 laps to go, leaving him with a 41st-place finish.
At Dover, he started 15th and finished 13th. At Pocono, Ragan started 21st and finished 23rd. At Michigan, Ragan fell off the lead lap and was scored 35th when the race was called for rain.
At Sonoma, Ragan started in ninth. He'd be involved in two wrecks during the day. On lap 30, when coming out of Turn 7, Martin Truex, Jr. forced him into the grass. When Ragan's car got back onto the racing surface, he clipped Truex from behind, sending Truex into the tire barriers. Later, following a restart on lap 79, Ragan was racing alongside Carl Edwards for position when, coming through the esses in the same spot as Truex's crash, Edwards' car bounced over the outside curb, sending him into Ragan, and sending both cars into the jersey barriers on the inside of the track. Ragan finished 39th.
Returning to Daytona for the Coke Zero 400, Ragan started eighth. He was involved in a single car spin on the back straightaway on lap 149 after contact with Landon Cassill, but was able to recover and finish 12th. At Kentucky, he started 25th and finished 18th. This was followed by a 21st-place finish at Indianapolis, a 17th-place finish at Pocono, and a 23rd-place finish at Watkins Glen. After the race at Homestead, in which Ragan finished 27th, MWR closed its doors leaving Ragan without a ride.
On January 19, 2016, it was announced that Ragan would drive the No. 23 Toyota Camry for BK Racing.
You can read more about David's racing career from Wikipedia: