Ajit Doval also met Sri Lankan Defence Secretary Major Gen (Retd.) Kamal Gunaratne on Friday.
National Security Advisor Ajit Doval on Saturday took part in the high-level trilateral maritime dialogue among India, Sri Lanka and the Maldives.
Sri Lanka is hosting the fourth trilateral meeting on maritime security cooperation with India and the Maldives.
The meeting is taking place after six years - the last meeting was held in New Delhi in 2014.
"The trilateral meeting among India, Sri Lanka and the Maldives on maritime and security cooperation gets underway," the High Commission of India in Colombo said in a tweet.
Sri Lanka's Foreign Minister and Leader of the House-Parliament, Dinesh Gunawardena, was the chief guest at the event, it said.
The meeting will be attended by observers from Bangladesh, Mauritius and Seychelles, the Sri Lankan military said Thursday.
Ajit Doval, who arrived in Colombo on Friday for the dialogue, on Friday met Maldivian Defence Minister Mariya Didi and held a cordial and detailed discussion on deepening bilateral partnership with the key island nation in the Indian Ocean.
Ajit Doval also met Sri Lankan Defence Secretary Major Gen (Retd.) Kamal Gunaratne on Friday and they agreed on several steps to further strengthen the "valuable" cooperation between the two countries which also contributes to peace and security in the region.
"NSA Ajit Doval met Major Gen(Retd.) Kamal Gunaratne, Defence Secretary of SriLanka & discussed matters pertaining to the growing defence and security partnership between the two countries," the Indian High Commission in Colombo said in a tweet.
The high-level trilateral meeting is designed to initiate collective action on maritime security including maritime domain awareness, legal regimes, train in search and rescue, maritime pollution response, information sharing, curbing piracy drugs arms and contraband trafficking in the Indian Ocean region.
On Thursday, the External Affairs Ministry in New Delhi said the NSA-level trilateral meeting had served as an effective platform for cooperation among Indian Ocean countries.
"The meeting will provide an opportunity for discussion on issues pertaining to cooperation in maritime security in the Indian Ocean region," the MEA said in a statement.
The meeting is taking place amidst China's attempts to spread its influence in the resource-rich Indo-Pacific region.
China views the Maldives as key to its Maritime Silk Road project in the Indian Ocean as it has already acquired Hambantota port in Sri Lanka and Djibouti in the Horn of Africa.