The valuables have an estimated preliminary worth of over 500 billion rupees ($11.2 billion), said Kerala Chief Secretary K. Jayakumar, catapulting the temple into the league of India's richest temples.
The thousands of necklaces, coins and precious stones have been kept in at least five underground vaults at the Sree Padmanabhaswamy Temple which is renowned for its intricate sculptures.
"We are yet to open one more secret chamber which has not been opened for nearly 140 years," Jayakumar told AFP.
The actual value of the treasure haul can be ascertained only after it is examined by the archaeological department, said Jayakumar.
The temple, dedicated to Hindu lord Vishnu, was built hundreds of years ago by the king of Travancore and donations by devotees have been kept in the temple's vaults since.
A necklace found on Thursday was 18 feet (six metres) long. Thousands of gold coins have also been found.
Since India achieved independence from Britain in 1947, a trust managed by descendants of the Travancore royal family has controlled the temple.
But India's Supreme Court recently ordered that the temple be managed by the state to ensure the security of valuables at the shrine.
Until now, the Thirupathy temple in southern Andhra Pradesh state was believed to be India's richest temple with offerings from devotees worth 320 billion rupees.
The revelation about the huge riches in the Padmanabhaswamy temple has forced police to sharply step install security cameras and alarms.
Authorities also plan to set up a commando force for security, said Kerala director general of police Jacob Punnoose.
"Now it?s known all over the world that the Padmanabhaswamy temple has jewels worth billions of rupees we have decided to assign it maximum security," Kerala Chief Minister Oommen Chandy told AFP.