Cosby High School was named for its proximity to Cosby Road. Once a major road through the county, it is now only about a mile long, running parallel to the more heavily-trafficked Hull Street Road. The road's namesake, Wilson Dance Cosby, was a local resident who worked thirty-five years as a county school bus driver.
Athletics
Cosby High School is a member of group AAA in the Virginia High School League. They are a part of the AAA Central Region and AAA Dominion District. Cosby has won the Dominion District All Sports Cup for the last five years.. In 2012, they won the Wells Fargo Cup, which honors the VHSL high school with the most prominent athletic department on the state level. They became the first Central Region team to win the cup in the 28-year history of the award.
Cheerleading
In 2010, Cosby's competitive cheerleading team won the school's first VHSL AAA State Championship. The Cosby Cheerleaders, in addition to winning the fourth straight Central VA SpiritFest competition in Charlottesville, won the "Triple Crown" in VHSL competition: Dominion District, Central Region, and State Championship. They were the first Dominion District team to make it to State Finals since 2008 and then the first Dominion District team to win a State Championship in Competitive Cheer; also, the first Central Region team to win a state championship in competitive cheer. In 2011, Cosby's competitive cheerleading team won their second VHSL AAA State Championship. They were the third team to ever win the crown back to back. In addition, the team once again won the "Triple Crown." winning the Dominion District, Central Region, and State Championships.
Soccer
In 2012, the Cosby Girls Soccer team won the AAA State Championship. They ended their season with an undefeated record of 23-0-1. In 2018, the Cosby Boys Soccer team won the class 6 State Championship, defeating Oakton 2-1.
Track and field
In 2012, the Cosby Girls Indoor Track team won the AAA State Title.
Wrestling
In 2011, Austin Coburn became Cosby's first individual state champion by winning the 171 pound weight class in wrestling.
Softball
In 2012, the Cosby softball team won their first state title by defeating Patrick Henry 3-2 and winning the Group AAA state championship.
A Health Science Specialty Center opened in the fall of 2007, with a goal of developing special partnerships with many community health organizations such as Bon Secours St. Francis Hospital, VCU School of Medicine, Chippenham/Johnston-Willis Medical Center, Brandermill Woods Retirement Center, and John Tyler Community College programs. The Health Science Specialty Center allows students to explore their interests of health care fields to prepare them for their future in health science.