Justice Mojisola Olatoregun of a Federal High Court in Lagos, Thursday, convicted Calistus Obi, a former acting Director-General of the Nigerian Maritime Administration and Safety Agency (NIMASA).
Mr Obi was charged with N136 million fraud by the Economic and Financial Crimes Commission (EFCC).
The court has, however, deferred sentencing to a later date.
Mr Obi was appointed the acting head of NIMASA two months after President Muhammadu Buhari assumed office in 2015.
Mr Buhari earlier fired Patrick Akpobolokemi as the Chief Executive Officer of the agency.
Mr Akpobolokemi is being prosecuted separately for corruption while in office.
In the charge filed against Mr Obi, he was alleged to have committed the offences on August 5, 2014.
According to the EFCC, he and a former staff of NIMASA allegedly conspired to convert money from NIMASA, with the knowledge that same were proceeds of stealing.
The offences contravene the provisions of Sections 15 and 18(a) of the Money Laundering Prohibitions (Amendment) Act, 2012.