India signed a pact to provide patrol boats and offered $500-million line of credit in the defence sector to Vietnam.
The agreement was clear sign of New Delhi increasing its presence in south-east Asia's geopolitical scenario.
It also elevated its ties with Vietnam from "strategic partnership" to "comprehensive strategic partnership" after the delegation-level talks between Prime Minister Narendra Modi and Vietnamese Prime Minister Nguyen Xuan Phuc.
"My conversation with PM Phuc was extensive," Modi said in a joint press address with his Vietnamese counterpart.
"We agreed to tap into the growing economic opportunities in the region," he said.
Both countries signed 12 agreements, including cooperation in the field of cyber security.
Modi arrived in Vietnam on Friday. It was the first prime ministerial visit from India to Vietnam in 15 years.