By the time he graduated high school he held numerous VHSL football records. Many have been broken but he still remains to this day in the top ten in many catergories. Those categories include: career scoring (618 points), rushing yards (7,428) and touchdowns (103); single season scoring (258 points), rushing yards (2,864) and touchdowns (43). His records for most career attempts, 100-yard games, and the streak of 26 consecutive games rushing 100-yards still stands today.
Not only was he a great football player he was also a standout out basketball player too. He played in a well known basketball tournament in Bristol, TN, the Arby's Classic. He still holds records for when he played in the tournament in 1988. His records include: most field goal attempts with 33 and most field goal attempted with 105.
Drafted by the Miami Dolphins in 1993. Kirby's best year as a pro came during the 1995 season as a member of the Miami Dolphins, rushing for 414 yards and catching 66 passes. He left Miami after a leg injury.
In 1996 he joined the San Francisco 49ers, taking over the starting role and sharing time with Garrison Hearst in 1997.