The death sentences of Mohammad Faramarzi, Mohsen Mazloum, Wafa Azarbar and Pejman Fatehi were upheld by the Supreme Court, the judiciary’s Mizan news said.
The men were accused of being recruited by Israel and training in Africa. It said they met Mossad chief David Barnea and travelled into Iran through Iraq's Kurdish region.
They were arrested in connection with a plot to bomb a weapons plant belonging to the Defence Ministry in Isfahan, Mizan added.
The executions came a few days after Iran executed a protester convicted of killing a police officer during the 2022 Mahsa Amini demonstrations.
Human rights groups said the men were all Kurdish prisoners of conscience and were detained on vague charges and tried in secret.
“Their case, marred by ambiguity, saw a lack of access to legal representation throughout their 18-month detention,” said the Hengaw Organisation for Human Rights, which monitors rights offences in the Kurdish areas of Iran.
“Even by the standards of the Islamic Republic of Iran, the minimum requirements for a fair trial were not met in their case. The proceedings of the case were shrouded in complete secrecy.”
The organisation said the men were permitted to meet their families on Sunday, for the first time since their arrest.
Relatives, including young children, had appealed for clemency at the weekend, and their mothers wrote to UN Deputy High Commissioner for Human Rights Neda Al Nashif, due to visit Iran next month, to call for their release.
Iran frequently claims to foil Israeli attacks throughout the country and often levels accusations of espionage against political prisoners.
Tehran accused the men of belonging to the Komala party, an exiled Iranian Kurdish opposition group based in the Kurdistan Region.
The group has officially denied the men were members, Hengaw said.
In December, it executed four men convicted of working for Mossad in Tehran and its West Azerbaijan and Hormozgan provinces.
Tehran is one of the world's biggest executioners, according to human rights groups.