General elections were held in Singapore on 21 September 1963 to elect all 51 members of the Legislative Assembly. This was the first and only general election held when Singapore was part of Malaysia as an autonomous state, and just days after it became fully independent from the United Kingdom on 16 September following full internal self-government in 1959. It was also the only election to date without any boundary changes to constituencies. The People's Action Party (PAP) under Lee Kuan Yew won 37 of the 51 seats, while 13 went to the Barisan Sosialis (BS) led by Lee Siew Choh, its left-wing splinter party. The United People's Party (UPP) secured one seat through its leader Ong Eng Guan, a former PAP member.

The ruling Alliance Party of Malaysia led by the United Malays National Organisation (UMNO) contested the election through its Singapore branch (SAP) in an attempt to unseat the PAP, straining PAP–UMNO relations. However, the Alliance lost all seven of its seats which they held in Singapore, including those in Malay dominated areas. In response, the PAP contested seats in Peninsular Malaysia during the 1964 federal election the following year, further deepening tensions and mistrust between the Alliance federal government and the PAP state government.

A total of 210 candidates contested the elections, marking the largest slate in Singapore for over six decades until it was surpassed in 2025. The ruling PAP fielded candidates in all 51 seats, while its breakaway parties, BS and the UPP, each put forward 46 and the SAP fielded 42. This was the last election in which any party other than the PAP contested more than half the parliamentary seats. With the two PAP splinter groups and the Alliance fielding nearly full slates, it became one of the most fiercely contested elections and posed a serious challenge to the ruling PAP. Voter turnout reached 95.11%, the highest at the time in Singapore's history.

This was the most recent general election in which the PAP received less than half of the popular vote, at only 47%, and the last parliamentary election to date where MPs (29 out of 51) were elected by a plurality due to the first-past-the-post voting system. It was also the last general election in which an incumbent minister was defeated until 2011 and the last general election in which all seats were contested until 2015. With the Independence of Singapore Agreement 1965, this election was the only one that was held when Singapore was a state of Malaysia. After independence, the elected members of the Legislative Assembly subsequently become members of the inaugural Parliament of Singapore.

Background Although the People's Action Party (PAP) had won 43 seats in the 1959 elections, they lost four seats in 1961 (two were from the by-election defeats, and two defected to the new United People's Party (UPP)). A further 13 legislators were expelled from PAP for voting against the government in a no-confidence motion on 20 July 1961; the dissidents subsequently formed a new party, the Barisan Sosialis (BS), alleging PAP as a communist front. The combination of by-election defeats, defections and expulsions reduced the PAP by 17 seats down to 26, leaving PAP with a one-seat majority.

On 3 July 1962, while the integration referendum debate was in procession, the PAP lost its majority following the resignation of legislator Ho Puay Choo, who later joined BS on 11 August. Five days later, UPP legislator S. V. Lingam rejoined PAP, giving it back its one-seat majority. However, the majority was lost again on 21 August following the death of health minister Ahmad Ibrahim, who was the MP for Sembawang. BS planned to field Lim Chin Siong to contest in a by-election, but it was not held.

On 31 August 1963, Singapore was declared fully independent from the United Kingdom (full internal self-government was granted in 1959) with PAP declared as trustees until the merger with Malaysia could be complete. On 3 September, Lee Kuan Yew dissolved the Legislative Assembly in accordance with procedure, the Proclamation of Malaysia was ratified on 16 September, and elections are to be held on 21 September. As part of the Malaysia Agreement, the head of government in Singapore were permitted to retain the title of "Prime Minister" despite there already being a prime minister of Malaysia, as Singapore were given more autonomy in some areas than the other states of Malaysia.

Timeline 3 SeptemberDissolution of 2nd Legislative Assembly12 SeptemberNomination Day21 SeptemberPolling day22 OctoberOpening of 3rd Legislative Assembly

Incumbents not standing for re-election The following incumbent elected members of the Legislative Assembly did not run in the 1963 election. Incumbent Party ConstituencyElected inAbdul Hamid JumatUMNOGeylang Serai1955Hoe Puay ChooBSBras Basah1959Ismail RahimPAPGeylang East1959G. KandasamyPAPKampong Kapor1959C. H. KohSPAJoo Chiat1959Lim Yew HockSPACairnhill1951Lin You EngBSMoulmein1959Low Por TuckBSHavelock1959John MammenPAPTelok Blangah1959Sahorah AhmatPAPSiglap1959Sheng Nam ChinBSNee Soon1959Tee Kim LengBSPasir Panjang1959

Campaign The elections, held in the midst of Singapore's merger with Malaysia, are remembered as the PAP's hardest-fought as the party faced intensive challenges from three other parties that fielded nearly full slates. BS collated with Parti Rakyat, and fielded candidates in all but two seats, while UPP had an unusually large number of candidates. Earlier that year on 2 February, as part of an anti-communist security operation, the PAP government with support of the Malaysian federal government and the British government had launched Operation Coldstore to detain several BS leaders, including Lim Chin Siong, which severely hampered BS.

On the final night of campaigning, PAP officials issued a sudden warning: if BS were to win the election and defeat the PAP, the federal government in Kuala Lumpur might deploy troops to Singapore and invoke emergency powers, bypassing the incoming BS-led government, allegedly due to its perceived pro-communist stance. This last-minute tactic, seen by many as fearmongering, left BS with no opportunity to respond. Nevertheless, it appeared to sway public sentiment and may have contributed significantly to the PAP's victory the following day.

The sole Workers' Party (WP) legislator David Marshall resigned from the party he founded and became the only independent. Another participant was Singapore Alliance, an extension of the ruling federal Alliance Party in Malaysia, which was a coalition consisting of the Singapore People's Alliance (SPA) along with the local branches of UMNO, the Malayan Chinese Association and Malayan Indian Congress. However, former Chief Minister and leader Lim Yew Hock opted not to run in the elections, citing a defamation campaign by the PAP.

Results In terms of votes, Cairnhill candidate Lim Kim San had the best scoring result of 66.46%; however, 29 out of the 51 constituencies had elected by plurality as a result of first-past-the-post voting. Delta's MP-elect Chan Choy Siong had the narrowest winning margin of 0.46%. A total of 92 candidates lost their election deposits, with the lowest being 0.72%, held by Moulmein's independent candidate Soo Tho Siu Hee.

By constituency