Tomo Kriznar, an envoy of the Slovenian president, was arrested in July in Darfur allegedly for not having a correct visa.
Slovenia has hosted talks to try to win over rebel groups that refused to join a peace deal in May between the government and one rebel faction.
Slovenia has still to react to the sentencing of the envoy.
Sudan's state news agency on Monday quoted Mohamed Ali al-Mardi, the justice minister, as saying: "The court sentenced the defendant to two years imprisonment and a fine of 500,000 dinars [$2,350] and confiscation of exhibits found with the defendant of photography equipment and films."
An African union (AU) source in Darfur said the Slovenian envoy had entered through neighbouring Chad and had been travelling with Darfur rebel groups, taking video footage and photographs.
The AU has a 7,000-strong force monitoring a shaky truce in Darfur.
Renegade commanders from the rebel Sudan Liberation Army and the Justice and Equality Movement (JEM) united with Ahmed Ibrahim Diraige, a former Darfur governor, to form the National Redemption Front (NRF), which attacked a Sudanese town just outside Darfur in June.
The rebel factions did not sign the May accord, saying it did not meet their basic demands of fair compensation for war victims and enough political representation in Khartoum.
Immediately prior to forming their alliance, the JEM leaders and Diraige had been in intense closed-door talks with the Slovenian president in Ljubljana.
Tens of thousands have been killed and 2.5million forced from their homes in more than three years of rape, killing and pillage in the region.