Jeffrey Moyo, a 37-year-old Zimbabwean, spent three weeks in jail last year and his trial started in January.
The New York Times has denied the charges, saying the accreditation of its journalists Christina Goldbaum and Joao Silva by a Zimbabwe Media Commission official was above board.
The two American journalists were expelled from Zimbabwe.
"Jeff has been convicted and sentenced to pay Zim$200,000 (about $615). He was charged with violating Section 36 of the Immigration Act," Moyo's lawyer, Doug Coltart, told Reuters.
Coltart said Moyo would appeal his conviction.
Critics say Zimbabwe's government, under President Emmerson Mnangagwa, has continued the authoritarian ways of his predecessor, the late Robert Mugabe, despite earlier promises to end rights abuses.
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