In 2004, Keselowski ran eight races for K Automotive in the NASCAR Craftsman Truck Series, followed by a complete schedule in 2005. He competed on a limited basis in both the NASCAR Nationwide and Truck Series in 2006. Keselowski started the 2007 season racing in the Nationwide Series until his team suspended operations in June. Later that month, he was called to drive for another team and scored them the Bud Pole Award, leading four times throughout the race while contending for the win. Keselowski was then hired by JR Motorsports and debuted in the # 88 Navy Chevrolet at Chicagoland Speedway in July 2007. In 14 starts, he scored five top 10 finishes for the team.Keselowski enjoyed a breakout year in 2008, finishing third in the NASCAR Nationwide Series point standings -- the highest finish for a Series regular. He garnered two wins (Nashville and Bristol) and claimed the series Lap Leader Award for 2008. Keselowski was also named the 2008 Nationwide Series Most Popular Driver, an award voted on by the fans.

On the strength of his Nationwide Series performance, Keselowski made his NASCAR Sprint Cup Series debut in late 2008. He drove the #25 GoDaddy.com Chevrolet for Hendrick Motorsports at Texas Motor Speedway in November, where he started 37th and finished 19th. Two weeks later, Keselowski raced the #25 at the Homestead-Miami Speedway in the season finale, starting 31st and finishing 23rd.

Keselowski will be behind the wheel of the #88 GoDaddy.com Chevrolet Impala for 18 Nationwide Series races in 2009. He’ll also drive the #25 GoDaddy.com car in the Sprint Cup Series for seven races in 2009. Teammates Dale Earnhardt Jr. and Tony Stewart will each drive the #5 GoDaddy.com Chevy for one race in the 2009 Nationwide Series ... Keselowski secured his first Sprint Cup Series win in just his fifth race at the Aaraon's 499 at Talladega on 4/26/09.