Fernando Flores filed the sexual harassment lawsuit in suburban Los Angeles, alleging the singer intentionally inflicted emotional distress.
He is seeking unspecified damages from the Grammy Award-winner and his former employer, Advanced Security Concepts Corp.
The lawsuit claims that Spears, among other things, exposed herself to Flores and summoned him to her bedroom while she was naked.
The bodyguard's employment with Spears appeared to be brief - his court filings state he started working for her in February and had "exhausted his administrative remedies" with a state agency by July.
Spears' publicist, Holly Shakoor, did not return e-mail messages seeking comment. A woman who answered the phone at Advanced Security Concepts declined to comment and refused to be identified.
Flores' suit also claims he witnessed Spears engage in inappropriate conduct around her young sons and once borrowed his belt to discipline them.
The singer remains under a court-ordered conservatorship in which her personal and financial affairs are controlled by her father and an attorney, and monitored by a judge. The conservatorship has prevented Spears from being deposed or testifying during previous cases in which she was sued.
Spears, 28, has frequent visits with her sons, who she had with ex-husband Kevin Federline. He has not sought any changes to their custody arrangement in recent months, court records show.
The lawsuit was first reported by celebrity website TMZ.com.