In a statement, the army said Kulbhushan Jadhav, who was arrested in March 2016, was an Indian intelligence official who aided and financed terrorist activities in the southwestern Balochistan province and the southern port city of Karachi.
“Today, [army chief] Gen Qamer Javed Bajwa has confirmed his death sentence,” a military statement said on Monday, without stating when the execution would take place.
Pakistan’s army released a video shortly after his arrest in which he confessed to having spent years sowing unrest in Pakistan and being tasked by India’s intelligence service with planning, coordinating and organising espionage and sabotage activities in Balochistan “aiming to destabilise and wage war against Pakistan”.
India has denied that he was a spy, calling the claims “baseless” and has said Pakistan executing him would be “premeditated murder”.
Pakistan accuses India of helping the separatist movement in Balochistan, a charge denied by India.
The government in Delhi says Pakistan aids separatist fighters in Kashmir.
Kashmir has been divided between India and Pakistan since the end of British rule in 1947.
Both countries claim the Himalayan territory in full and have fought three wars over Kashmir.
Last September, tension between the neighbours escalated after fighters killed 19 Indian soldiers at an army camp in Kashmir, an attack India blamed on Pakistan-based fighters.
Pakistan denies backing the fighters, saying it only offers political support to the Muslim people of Indian-controlled Kashmir.
In 2013, an Indian national sentenced to death for spying in Pakistan was killed in jail after being attacked by fellow inmates. Sarabjit Singh had been on death row for 16 years.
In 1999 another Indian man, Sheikh Shamim, was hanged in a Pakistani jail almost 10 years after he was caught “red-handed” near the border and arrested on charges of spying.