"The plant has been set up for people’s welfare," said the ruling on the Kudankulam plant.
"Necessary clearances have been taken by the government, and development of the nuclear power plant is important for India," it added.
The Russian-built Kudankulam plant is the country’s biggest nuclear power project and is designed to help meet a surging demand for electricity in Asia’s third-largest economy where power blackouts are frequent.
Plans for the facility were first drawn up in 1988 and two of the reactors now are in place.
The plant was supposed to open in 2011 but large, often violent protests, by locals worried about radiation have delayed the start-up.
Several petitions had been filed before the top court by anti-nuclear activists challenging the project on safety grounds.
"We have to strike a balance between larger interest and economic necessities," Judges KS Panicker Radhakrishnan and Dipak Mishra said in the ruling.
At the same time, the court ordered the government to submit a final report on the plant’s safety and waste disposal arrangements to deal with hazardous material.
