Amalia Tabata-Pereira, 44, pleaded guilty in Hillsborough Circuit Court on Wednesday on charges of kidnapping, interference with custody and impersonating a public officer.
In March 2009, Tabata-Pereira posed as an immigration official and threatened a migrant worker and her boyfriend with deportation if they didn't give their baby girl to Pereira, prosecutors said.
The mother complied, then contacted police six hours later to report a kidnapping.
Tabata-Pereira will be sentenced Sept. 30.
A Pirates spokesman says Tabata has long avoided contact with his estranged wife and he continues to work with his lawyers to complete their pending divorce.