Almost half a century later, his vision appears set to be realised, with the Association of Southeast Asian Nations (ASEAN) announcing on Friday it has agreed in principle to admit East Timor, officially known as Timor Leste, as the group's 11th member.
Ramos-Horta, 72, who left retirement this year to clinch the country's presidency for a second time, told Reuters the dream has been long-held.
"The very first time I talked about this I was only 24, or 25," he said by telephone from the capital Dili.
"I went to Jakarta and met with then Indonesian foreign minister Adam Malik and I had zero diplomatic experience but I knew that regional integration, a membership in ASEAN, and a close relationship with Australia and Indonesia was very important to the future of Timor Leste."
At the time, East Timor was ruled by Portugal, although it was clear that Lisbon would soon relinquish its colony.
East Timor was later annexed by Indonesia and gained full independence only in 2002.
At a summit in the Cambodian capital Phnom Penh this week, ASEAN said East Timor would be granted observer status at high-level meetings of the bloc as it formulates a "roadmap for full membership".
The once aspiring diplomat, Ramos-Horta, is now one of East Timor's best-known political figures.
He spent decades as the exiled spokesperson for East Timorese guerrilla fighters when the country was opposing Indonesian occupation, a struggle for which he was awarded the Nobel prize in 1996.
He served as the country's first foreign minister, prime minister from 2006 to 2007 and president from 2007 to 2012, during which time he survived an assassination attempt by rebel soldiers.
Ramos-Horta said becoming a fully-fledged ASEAN member would "not happen tomorrow" and could still take several years but would ultimately benefit his young nation.
East Timor celebrated 20 years of independence this year but the country of 1.3 million people is heavily dependent on dwindling reserves of oil and gas.
It has struggled for years with bouts of instability, political regeneration and the challenge of diversifying its economy.
ASEAN membership would open up his country to wider diplomatic relations with ASEAN's dialogue partners, greater opportunities for foreign direct investment and provide Timorese with better education and employment opportunities, Ramos-Horta said.
"There will be more facilities for Timorese to travel across ASEAN to study and work," he said.
"And there will be a lot of pressure on Timorese elites, our own government to work, to deliver because it doesn't only come with rights and privileges but a lot of burden of responsibility."
