Racing prior to NASCAREdit
Hamlin began his racing career in 1988, at the age of 7 years old, racing go-karts. By 1997 at 15 he won the WKA manufacturers cup at the age of 16, he was racing Ministocks. In his first stock car race, at Langley Speedway, Hamlin won the pole position, and won the race. He then progressed to the Grand Stock division in 1998, and moved on to Late Model Stock Cars in 2000. In 2002, he won ten Late Model races, and surpassed that in 2003 with 25 wins, and 30 poles, out of 36 races. In 2004, while competing full time in Late Model Stock Cars, Hamlin was signed to a driver development contract with Joe Gibbs Racing.
In 2004, Hamlin competed in five NASCAR Craftsman Truck Series (NCTS) races with EJP Racing, and had a tenth-place finish in his NASCAR debut at Indianapolis Raceway Park. He later ran his first career ARCA RE/MAX Series race at Talladega Superspeedway, finishing third in the #10 Pontiac owned by Andy Hillenburg. His final start of the year came at Darlington Raceway, when he made his Busch Series debut. He qualified twenty-seventh but finished eighth in the #18 Joe Gibbs Driven Performance Oil Chevy.
Hamlin ran the full season in 2005 after he replaced Mike Bliss in the #20 Rockwell Automation Chevrolet in the Busch Series. He ended up finishing 5th in the final championship points standings as a rookie in that series, with 11 top 10's and earnings of $1,064,110.00. Hamlin also ran his first Nextel Cup Series races in 2005, making his Cup debut at Kansas Speedway as driver of the #11 FedEx Chevrolet for the 2006 season, after Jason Leffler was released, and made seven starts in in the Cup series in 2005. He finished the Cup season with three top 10 finishes in those seven starts and one pole at Phoenix International Raceway.
In 2006, Hamlin ran his first full season in the NASCAR Nextel Cup Series, and during the year he drove in both the Nextel Cup and Busch Series full-time. In Hamlin's first restrictor plate race as a Nextel Cup driver, he beat all the previous year's (2005 season) pole winners in the 70-lap 2006 Budweiser Shootout. Hamlin became the first Rookie of the Year candidate to take home the Shootout victory. Hamlin achieved his first career Busch Series victory at Autodromo Hermanos Rodriguez (March 5). On June 11, Hamlin scored his first career Cup Series win at the Pocono 500, where he also won his second career pole. He achieved his second career win on July 23, in the Pennsylvania 500 also at Pocono Raceway becoming only the 2nd rookie in Nextel Cup history to sweep both races at a track during the same season (Jimmie Johnson did so at Dover International Speedway in his rookie season in 2002), both from the pole position. In the Cup Series, Hamlin won the Raybestos Rookie of the Year award and finished third in the final Cup standings, scoring the highest points finish ever for a rookie in the modern era of NASCAR. Hamlin thus became the first ever rookie to make the Chase for the NEXTEL Cup. 
Hamlin started the 2007 Cup season by finishing 28th in the Daytona 500. He won his third career cup race at the Lenox Industrial Tools 300 at New Hampshire International Speedway. Hamlin clinched a spot in the Chase for the Cup and was seeded sixth, 50 points behind the leader, but finished 12th overall in the final standings. In the Nationwide Series, Hamlin scored three victories including Darlington, Michigan, and Dover in the #20 Rockwell Automation Chevy.
In 2008, Hamlin had a near identical season as before, but moved up to eighth in points, and won early in the season at Martinsville Speedway. He led 381 out of 410 laps at in the 2008 Crown Royal Presents the Dan Lowry 400, the most dominant effort of a driver since 2000. but cut a tire and finished 24th. He won three races in the Nationwide Series, driving both the #18 and #20 entries for Gibbs, as well as the #32 Dollar General/Haas Avocados Car for Braun Racing.
He continued driving the #11 car in Sprint Cup in 2009, as well as sharing the #20 car for Gibbs in the Nationwide Series. Hamlin won his fifth career race at Pocono on August 3, 2009. Hamlin boldly stated at the final restart "I'm going to win this race." He followed through on the statement, moving from sixth to first and snapping a 50 race win-less streak. The win was Hamlin's third at the Pocono tri-oval. It was especially emotional for the #11 team as Hamlin had lost his grandmother, Thelma Clark, that Friday.
Hamlin once again dominated the race at Richmond and finally won at his home track. On October 25, 2009 Hamlin held off Jimmie Johnson to win the Tums Fast Relief 500 at Martinsville. Hamlin guaranteed that he would win this race after he came in 2nd in the spring race.
Hamlin then went on to win the Ford 400 at the 2009 NASCAR Sprint Cup Series Finale at Homestead-Miami Speedway, capping off his 2009 season 5th in the overall standings with 4 wins, 15 top 5's and 20 top 10's. Hamlin took the lead after starting the race in 38th position and he led a total of 70 laps to capture his 4th win of the 2009 season.
After the 2009 season ended, Hamlin had surgical repair to the meniscus of this right knee, which was done on December 16. On 22 January 2010, Hamlin tore the anterior cruciate ligament in his left knee while playing pickup basketball. With the 2010 NASCAR season only two weeks hence, surgery to repair the injury is being postponed until after the season ends. The injury will not affect Hamlin's ability to compete in NASCAR.