Ioannis Aidinidis, 46, who was born in Georgia and now lives in Munich, Germany, was arrested on May 16 and has been charged under the United Kingdom's National Security Act.
Prosecutor Daniel Ingham told London's Westminster Magistrates' Court that Aidinidiswas accused of travelling to the UK twice, in April and in May, to carry out surveillance of the journalist.
Iran International is critical of the Iranian government.
Aidinidis took photos of cars, houses and other addresses associated with the journalist, Ingham said, and on the second trip allegedly installed a covert camera hidden in a sock in a tree that was able to send data to unknown recipients.
Ingham said messages on Aidinidis' phone indicated he was being funded by people abroad and that separate evidence suggested he carried out surveillance on a defence firm in Italy in between his trips to the UK.
Police said his actions were believed to be on behalf of Iran.
Aidinidis was not asked to enter a plea at this stage and was remanded in custody until his next hearing on June 19.
Iran's government has repeatedly denied involvement in attacks or plots in the UK.
"We know this may cause concern for many people here in the UK, and particularly those working in Persian-language media," Helen Flanagan, head of counter-terrorism policing in London, said.
"We continue to work closely with a number of organisations and individuals to provide them with advice and support around their safety and security and this includes the specific individual and organisation linked to this investigation."
In April, three people were charged over an attempted arson attack on premises linked to Iran International in northwest London, although the fire caused no damage or injuries.
UK police have previously said they were looking at whether there were any Iranian links to that incident and a series of arson attacks on Jewish sites in the capital.
A pro-Iranian group called Ashab al-Yamin al-Islamiyya had claimed responsibility for most of the incidents.
