- 15–16 January 1974 – During a visit by Japanese Prime Minister Kakuei Tanaka, widespread riots break out, leading to the formal disbanding of President Suharto's personal assistants
- 16 January 1904 – Dewi Sartika (pictured) establishes the first school for girls in Indonesia
- 26 January 1949 – The national flag carrier Garuda Indonesia is established
- 27 January 2008 – Former president Suharto dies, the first Indonesian president to do so since Sukarno in 1970
- 31 January 1926 – Hasyim Asy'ari establishes the conservative Muslim organisation Nahdlatul Ulama as a reaction to the modernist Muhammadiyah
- 8 February 2002 – Ada Apa dengan Cinta?, credited with reinvigorating the Indonesian film industry, is released
- 13 February 2002 – The Malino II Accord, an attempt to stop the Maluku sectarian conflict, is signed
- 15 February 1950 – The People's Representative Council holds its first meeting
- 17 February 1745 – Pakubuwana II establishes the Surakarta Sunanate in Surakarta
- 22 February 1978 – Istiqlal Mosque (pictured) in Jakarta, the largest mosque in Southeast Asia, is inaugurated
- 1 March 1949 – In a show of force, Indonesian soldiers under Colonel Suharto recapture the capital at Yogyakarta
- 9 March 1942 – Governor-General Tjarda van Starkenborgh Stachouwer capitulates to invading Japanese forces, leading to a three-year long occupation
- 11 March 1966 – President Sukarno signs the Supersemar, which is used by Suharto to take greater control over the country
- 12 March 1946 – The first female cabinet member, Maria Ulfah Santoso (pictured), takes office
- 24 March 2019 – Jakarta MRT opened to the public, and the first rapid transit in Indonesia
- 26 March 1873 – A Dutch expedition bombards Banda Aceh; this is the opening salvo of the Aceh War
- 10 April 1815 – Mount Tambora, on the island of Sumbawa, erupts, leading to the year without a summer
- 18 April 1955 – The Asian–African Conference, an important step towards the establishment of the Non-Aligned Movement, begins (building pictured)
- 20 April 1975 – Taman Mini Indonesia Indah, a large cultural park in Jakarta, opens
- 21 April 1879 – Women's rights figure Kartini is born; this date continues to be celebrated as Kartini Day
- 24 April 1778 – The Royal Batavian Society of Arts and Sciences, one of the first scientific groups in the country, is established
- 1 May 1547 – The port city of Semarang in Central Java is established
- 2 May 1889 – Ki Hajar Dewantara, founder of the Taman Siswa schools, is born; the date continues to be celebrated as Education Day in Indonesia
- 21 May 1998 – President Suharto resigns after several months of unrest, ending the 32-year-long New Order
- 27 May 2006 – A powerful earthquake kills thousands of people in the Yogyakarta region in central Java
- 30 May 1619 – Dutch troops raze the city of Jayakarta, later establishing their capital over the rubble
- 1 June 1945 – President Sukarno first outlines his idea of Pancasila, now Indonesia's state philosophy
- 7 June 1999 – Indonesia's first free and fair national elections since 1955 take place, but no party gains a majority
- 10 June 2009 – The Suramadu Bridge (pictured), the longest in Indonesia, opens
- 17 June 1864 – The first railway track in Indonesia was laid between Semarang and Tanggung, Central Java
- 27 June 1970 – President Sukarno becomes the first Indonesian president to die; he is buried in Blitar, East Java
- 5 July 1959 – President Sukarno issues a decree dissolving the Constituent Assembly and reintroducing the Constitution of 1945
- 8 July 1976 – The Palapa A1, Indonesia's first communication satellite, is launched from Cape Canaveral
- 12 July 1975 – The National Monument (pictured) in Jakarta is dedicated
- 23 July 2001 – Indonesia's first female president, Megawati Sukarnoputri, takes office
- 29 July 1947 – A flight carrying medical supplies is shot down over Bantul; this date is commemorated as a service day for the Indonesian Air Force
- 4 August 1992 – Susi Susanti and Alan Budikusuma win Indonesia's first gold medals at the Olympics in Barcelona
- 15 August 1962 – The New York Agreement, transferring Western New Guinea to Indonesia, is signed
- 17 August 1945 – Indonesia proclaims its independence (pictured)
- 24 August 1962 – The oldest television network in Indonesia, TVRI, begins broadcasting
- 26–27 August 1883 – In the Sunda Strait, Krakatoa erupts, killing 36,417 people
- 14 September 1906 – Dutch forces land at Sanur Beach (pictured), beginning the capture of Bali
- 18 September 1811 – After a several-month British invasion, the Dutch government surrenders, leading to three years of British rule
- 27 September 1950 – Indonesia joins the United Nations
- 29 September 1955 – Indonesia holds its first general parliamentary elections; these prove to be the last free ones until 1999
- 30 September 1965 – Members of the Indonesian Armed Forces initiate a failed coup d'état, leading to a purge against the communist party
- 5 October 1945 – The Indonesian National Armed Forces are established as the Tentara Keamanan Rakjat
- 12 October 2002 – A series of blasts in Bali kill 202, the most devastating terrorist attack in Indonesian history
- 17 October 2023 – The Whoosh High-speed rail (pictured) inagruated by President Joko Widodo which connecting Jakarta to Bandung, and first High-speed rail in ASEAN and Southern Hemisphere
- 20 October 1999 – The first freely-elected President of Indonesia, Abdurrahman Wahid, takes office
- 28 October 1928 – At the Youth Conference in Batavia, the Youth Pledge, promoting a united Indonesia, is read
- 28 October 1928 – WR Supratman first performs "Indonesia Raya", which later becomes Indonesia's national anthem
- 6 November 1940 – The first native Indonesian Roman Catholic bishop, Albertus Soegijapranata (pictured), is consecrated
- 10 November 1945 – British forces launch a major offensive on Surabaya, driving Indonesian soldiers out of the city; now celebrated as Heroes' Day
- 12 November 1991 – Indonesian troops kill more than 250 mourners in East Timor, turning international opinion against Suharto's government
- 15 November 1947 – Negotiations for the Linggadjati Agreement, the first attempt at a ceasefire between Indonesian and Dutch troops, conclude
- 18 November 1912 – The modernist Islamic organization Muhammadiyah is established by Ahmad Dahlan in Yogyakarta
- 7 December 1975 – Indonesian troops invade modern-day East Timor, beginning a 24-year occupation
- 13 December 1937 – The Indonesian state news agency Antara is established
- 19 December 1948 – The Dutch launch Operation Kraai and capture the national capital at Yogyakarta
- 26 December 2004 – A large earthquake strikes north of Aceh; the resulting tsunami (pictured) kills at least 131,028 in Indonesia alone
- 27 December 1949 – The Dutch formally recognise Indonesian sovereignty after several months of negotiations, ending the revolution