Borkowski grew up in Middlebury, Connecticut, and began racing Quarter Midgets at the Silver City Quarter Midget Club in Meriden, Connecticut. He competed in Quarter Midgets from 1981 to 1988, winning four New England States Championships.
At sixteen, Borkowski transitioned to full-size cars, competing in the 1989 Spenard David School and 1990 Bertil Roos School Racing Series. He won three out of seven races, secured two pole positions, and finished on the podium five times. In 1990, Borkowski dominated the SCCA's New England States Road Racing and North Atlantic Road Racing Championships with seven wins, two track records, seven pole positions, and eight fastest race laps.
Borkowski turned pro in 1991, competing in SCCA's Pro Sports 2000 Series, where he won Rookie of the Year. He continued his success in the 1992 and 1993 Pro Sports 2000 Championships, capturing five wins, eleven podiums, nine track records, four pole positions, and the 1993 Series Championship. In 1992, Borkowski co-piloted the Oldsmobile Aerotech, setting multiple FIA World Speed Records.
In 1997, Borkowski competed for Team Rahal Letterman in partnership with Tom Gloy Racing in the Trans-Am Series, collecting two wins, finishing third in the overall championship, and earning Rookie of the Year honors.
In 1995, Borkowski ran a limited schedule in Indy Lights with Team Medlin, finishing in the top ten in all six races, with a best finish of fourth at Belle Isle Park in Detroit. He also competed in the 24 Hours of Daytona as a factory driver for the #1 Oldsmobile Aurora GTS-1 in 1996. Borkowski returned to Indy Lights in 1998 under Team Rahal Letterman but had limited success. He also ran his second 24 Hours of Daytona, campaigning a Tom Gloy fielded GT1 Ford Mustang Cobra, finishing third in class.
Borkowski had a limited NASCAR career, competing in one Winston West Series, one Busch North Series, one Craftsman Truck Series, and nine Busch Series events between 1999 and 2003. His best finish was a tenth at Talladega Superspeedway in 2000 driving for Bill Davis Racing.
Borkowski's career in sports car racing included stints with Brumos Racing, Speedsource, Michael Shank Racing, Playboy Racing, and Stevenson Motorsports. He drove a variety of cars, including Daytona Prototypes, a Nissan 350Z, and a Chevrolet Camaro GT.R.
Borkowski also competed in the Rolex Sports Car Series, driving a Porsche-powered Daytona Prototype alongside David Donohue in 2003. Together, they won three races and finished second overall in the series championship.
Borkowski was awarded the Team USA Scholarship to compete at the Formula Ford Festival at Brands Hatch in 1994. He also received recognition for his achievements in the SCCA Pro Sports 2000 Series.