The report Tuesday said Iran's agents freed Heshmatollah Attarzadeh from his abductors and returned him safely to Iran.
Attarzadeh, Iran's commercial attache in Peshawar, was kidnapped November 2008.
The report said the diplomat was freed "in a complicated intelligence operation."
The operation marks the latest success by Iran's intelligence services broadcast on television. Last month, Iran captured Abdulmalik Rigi, leader of an armed Sunni opposition group whose insurgency in southeast Iran had destabilized the border region with Pakistan.