| Date | Event |
| 20 May 2002 | Timor-Leste gains its independence from Indonesia and is recognised as an ASEAN observer. |
| 26 July 2005 | After a case-by-case review and a delay in Pakistan's admission to the ASEAN Regional Forum due to India's disagreement, Timor-Leste joins the ASEAN Regional Forum, during the Twelfth Meeting of the ARF in Vientiane, Laos. |
| 13 January 2007 | Timor-Leste accedes to the Treaty of Amity and Cooperation in Southeast Asia. |
| 4 March 2011 | Timor-Leste officially applies for membership in ASEAN. |
| 6 July 2019 | ASEAN fact-finding mission on Timor-Leste is formed. This fact-finding mission investigates the eligibility and readiness of Timor-Leste to join the ASEAN Community. This consists of three pillars: the ASEAN Political-Security Community (APSC), the ASEAN Economic Community (AEC) and the ASEAN Socio-Cultural Community (ASCC). |
| 22 July 2019 | Timor-Leste sends delegations to the ASEAN Secretariat Technical Meeting. A delegation of 20, the largest ever delegation of East Timorese Government officials to visit the ASEAN Secretariat prior to Timor-Leste's joining, led and coordinated by the Directorate-General for ASEAN Affairs in the Ministry of Foreign Affairs and Cooperation. The delegation is composed of Director-Generals and Focal Points from line ministries working towards ASEAN accession across all the three pillars. This covers various important issues, which include learning about the ASEAN institutional framework and organic structure, decision-making bodies and processes, legal instruments and agreements, and technical cooperation. |
| 3 September 2019 | APSC Screening of Timor-Leste starts. |
| 6 July 2022 | ASCC Screening of Timor-Leste starts. |
| 19 July 2022 | AEC Screening of Timor-Leste starts. During the three-day AEC Fact-Finding Mission, delegates met with key Timor-Leste ministries/government agencies involved in the country's accession to the ASEAN Economic Agreements, including the Ministry of Finance, the Ministry of Petroleum and Minerals, the Ministry of Tourism, Trade and Industry, the Ministry of Agriculture and Fisheries, the Ministry of Public Works, the Ministry of Transport and Communication, the Customs Authority, and the Secretariat of State for Professional Training and Labor (SoSPTE). There were also meetings with Timor-Leste's Chambers of Commerce and Industry, as well as the business community. |
| 11 November 2022 | ASEAN agrees "in principle" to admit Timor-Leste; the country gains observer status at all high-level ASEAN meetings. |
| 11 May 2023 | ASEAN members finalise a dedicated road map for Timor-Leste to facilitate its full membership in the bloc. The roadmap requires Timor-Leste to align its laws and institutions with all three ASEAN pillars (APSC, AEC, and ASCC), improve human resources with strong English capacity to participate in ASEAN meetings, and upgrade basic infrastructure like airports, ports, roads, telecommunications, and hotels. It also includes readiness to contribute financially to ASEAN and to host and coordinate ASEAN activities. |
| 25 October 2025 | Timor-Leste deposited its instruments of accession to ASEAN, and accedes to the Southeast Asian Nuclear-Weapon-Free Zone Treaty. |
| 26 October 2025 | Timor-Leste is elevated to an ASEAN member state with signing of the Declaration on the Admission of Timor-Leste into ASEAN. |
