Cobb began racing in 1991 at Lakeside Speedway in Kansas City, where her father Joe Cobb also competed in the modified division. Her path to NASCAR was gradual, built through the ARCA Racing Series starting in 2002, where she recorded three top-ten finishes in three starts in 2004 while driving for Keith Murt. That same year she made her NASCAR Busch Series debut at Homestead-Miami Speedway, driving for Keith Coleman Racing.
In 2006, Cobb launched a clothing line for female race fans called Driver Boutique, channeling its proceeds into her racing program. The venture illustrated her approach throughout her career: finding creative ways to fund and sustain her presence in a financially demanding sport.
Cobb's most significant step came in 2010 when she purchased the assets of the No. 10 truck team from Rick Crawford's Circle Bar Racing operation and established herself as both driver and team owner in the NASCAR Camping World Truck Series. That season she became the highest female points finisher in history across any of the three major NASCAR series, placing 17th in the standings.
She continued at the helm of Jennifer Jo Cobb Racing in subsequent years, running full schedules or partial schedules in the Truck Series while making selected appearances in the Nationwide Series. In 2011, she set another benchmark by finishing sixth at the NextEra Energy Resources 250 at Daytona — the highest finish by a female driver in Truck Series history at that point. That record would stand for nine years until Natalie Decker surpassed it with a fifth-place finish at the same race in 2020.
Cobb also used her platform for outreach. In early 2011, partnering with U.S. Army Family and MWR Command, she launched Driven 2 Honor, a promotion honoring women in the U.S. military, hosting female service members and their guests at the first five Nationwide races of the season.
Throughout the 2012 to 2018 period, Cobb ran regular Truck Series campaigns in her No. 10 Chevrolet alongside occasional Nationwide Series starts. She also expanded her international presence, making her NASCAR Whelen Euro Series debut in 2018 at Circuit Ricardo Tormo in Valencia with Racing Total.
Two incidents in 2015 drew significant attention. At the Lucas Oil 200, Cobb approached Tyler Reddick's truck on foot after being spun out, resulting in a $5,000 fine — particularly closely watched because it followed the rule changes implemented after the fatal Kevin Ward Jr. incident. During practice for the Chevrolet Silverado 250 at Canadian Tire Motorsport Park, NASCAR penalized her $5,000 for having a non-engine electronic component (a cell phone) in her truck, with an additional $2,500 fine because she was still on probation. She became the first driver penalized under the no-cell-phone rule introduced after the 2012 Daytona 500.
In 2020, Cobb led a career-high 16 laps at Talladega Superspeedway, one of the stronger showings of her career before finishing 24th. The following year she was announced for a NASCAR Cup Series debut at Talladega with Rick Ware Racing, but NASCAR did not approve the entry, citing the need for prior Cup experience given that the race would have been her first time in a Cup car. She was replaced by J. J. Yeley.
By 2022, citing funding and equipment difficulties, Cobb scaled her operation back to part-time competition. The 2025 season was the first since her 2008 debut that she did not compete in the Truck Series.
Jennifer Cobb's career is notable for its longevity and its dual dimension as both competitor and team owner. For over fifteen years she remained a consistent presence in NASCAR's national series without the backing of large factory support, relying on owner-driver resourcefulness and personal sponsorship to sustain her program. Her record-setting points finish in 2010 and her long-standing top-finish record in the Truck Series positioned her as one of the more significant female competitors of her era in American stock car racing. The Driven 2 Honor initiative also extended her legacy beyond the results sheet.