The ICJ ruled that Pakistan must review the death sentence for Jadhav pronounced by a Pakistani military court.
Welcoming the verdict of the International Court of Justice on Indian national Kulbhushan Jadhav, Prime Minister Narendra Modi on Wednesday said "truth and justice" have prevailed.
He also said his government will "always work for the safety and welfare of every Indian".
In a major victory for India, the ICJ ruled that Pakistan must review the death sentence for Jadhav pronounced by a Pakistani military court.
Jadhav, 49, a retired Indian Navy officer, was sentenced to death on charges of "espionage and terrorism" after a closed trial in April 2017. His sentencing evoked a sharp reaction in India.
"We welcome today's verdict in the @CIJ_ICJ. Truth and justice have prevailed. Congratulations to the ICJ for a verdict based on extensive study of facts," the prime minister tweeted.
He said he is sure that Jadhav "will get justice".
A bench led by President of the court Judge Abdulqawi Ahmed Yusuf ordered an "effective review and reconsideration of the conviction and sentence of Mr Kulbhushan Sudhir Jadhav".
According to the ICJ, Pakistan "deprived the Republic of India of the right to communicate with and have access to Mr Kulbhushan Sudhir Jadhav, to visit him in detention and to arrange for his legal representation".
Other BJP leaders also hailed the International Court of Justice verdict in the Kulbhushan Jadhav case, with Defence Minister Rajnath Singh describing it as a "big victory" for India.
Former External Affairs Minister Sushma Swaraj also called it a great victory for India.
"The ICJ's verdict on Kulbhushan Jadhav is big victory for India. The ICJ directing Pakistan to grant consular access to Jadhav and asking them to review the conviction and the sentence is a welcome decision. It is also a big win for PM Narendra Modi's diplomatic initiative," Singh said.
Swaraj "wholeheartedly" welcomed the verdict and hoped that it will provide the much needed solace to the family members of Jadhav. "I wholeheartedly welcome the verdict of International Court of Justice in the case of Kulbhushan Jadhav. It is a great victory for India," she tweeted.
She thanked Prime Minister Narendra Modi for taking the case to the ICJ and senior advocate Harish Salve for arguing the matter very effectively and successfully.
BJP spokesperson Nalin Kohli termed it a significant legal victory for India and a major step in ensuring justice for Jadav.
The verdict "confirms the efficacy of the Modi government's diplomatic, strategic and legal efforts in protecting the interests of the country and our citizens", he said, adding that credit is also due to Salve for putting across India's points in a succinct and effective manner before the ICJ.
Some ruling party leaders also had a dig at Pakistan after the neighbouring country claimed that the ICJ verdict was a win for it.
"Not your fault... Judgment delivered in English," Union minister Giriraj Singh tweeted, tagging a Pakistan government tweet claiming win.
(With PTI inputs)
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
 "File Photo:")
){kind=small}
){kind=small}
){kind=small}
){kind=small}
)
){kind=small}
){kind=small}
)
)
)
)
)
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}