Associated Investigative Services of Orlando, Fla., is seeking $27,000 in unpaid fees from Zimmerman and his lawyer, Mark O'Mara, the Orlando Sentinel reported.
The company filed the suit Friday in Orange County.
Court papers show an elaborate plan to get Zimmerman into hiding after his release from jail. They included driving him to a resort, having him change in a men's room and then, using a different vehicle, moving him to a safe house.
O'Mara called the company's charges "exorbitant" but said he has paid $40,000. The invoices included in the company's court filings show it billed Zimmerman $66,000 for 21 days, including seven days when he was in the Seminole County Jail, the Sentinel reported.
Zimmerman, 29, was an unofficial neighborhood watch volunteer when he shot Trayvon Martin, 17, in a gated community in Sanford. Zimmerman says he was acting in self-defense after Martin attacked him, but the transcript of his call to 911 show he continued to tail Martin after a dispatcher suggested he back off.
O'Mara said Zimmerman is living in a safe house in Seminole County with a security system that costs $700 a week. He said his client rarely leaves the house and has gained a lot of weight.