The lawsuit, filed on Wednesday, alleges Sandusky sexually abused the boy more than 100 times from 1992 to 1996 after meeting him through Second Mile, the charity he founded. Sandusky then threatened the boy's family to keep quiet, according to the lawsuit.
The abuse allegedly happened at Sandusky's home, at Penn State facilities and on at least one bowl game trip.
The plaintiff is not among the eight victims named in a grand jury report released earlier this month that accuses Sandusky of abuse over 15 years.
Sandusky has acknowledged showering and embracing young boys but denies molesting them.
The Associated Press contributed to this report.