General elections were held in Malaysia on Sunday, 21 March 2004. Voting took place in all 219 parliamentary constituencies, each electing one Member of Parliament to the Dewan Rakyat, the dominant house of Parliament. They were the first elections for Abdullah Ahmad Badawi as Prime Minister following his appointment in 2003. State elections also took place in 505 state constituencies in twelve of the thirteen states (except Sarawak) on the same day, which also marked the first time Sabah held its state election parallel with the other states of Peninsular Malaysia.

The result was a landslide victory for the Barisan Nasional (BN) coalition, which received 64% of the vote (and would have gained a higher vote had all seats been contested) and won 198 seats to the combined opposition parties' 20 seats, with one independent. This was the largest majority that BN had won since 1978. The dominant party in BN, the United Malays National Organisation (UMNO), won 109 seats, a gain of 37. UMNO's allies also gained seats; the Malaysian Chinese Association (MCA) won 31 seats, a gain of two, and the Malaysian Indian Congress (MIC) won nine seats, a gain of two.

The Pan-Malaysian Islamic Party (PAS) managed to retain only seven of its 27 seats. PAS ran on a platform promising an Islamic state, which turned off many moderate voters. In addition, the PAS leader, Abdul Hadi Awang, lost his parliamentary seat. Another opposition party, the People's Justice Party (PKR), lost four of its five seats. After five recounts, the party's leader, Wan Azizah Wan Ismail (the wife of imprisoned former Deputy Prime Minister Anwar Ibrahim), retained her seat with a majority of just 590 votes.

The third opposition party, the Democratic Action Party (DAP), which was routed in the 1999 elections, improved its performance with the re-election of party chairman Lim Kit Siang in Ipoh Timor seat and his deputy, Karpal Singh in Bukit Gelugor seat although party secretary-general Kerk Kim Hock lost his seat. The DAP won 12 seats and regained the official leadership of the opposition in the national parliament from PAS. Most candidates who campaigned on platforms of Islamic issues lost their seats. This was a significant turnaround compared to the previous elections, where generally the more "Islamic" candidates had a greater chance of winning in the Malay heartland.

On 2 March, the tenth national parliament and all state assemblies in Malaysia (with the exception of Sarawak) were dissolved by the Yang di-Pertuan Agong upon the advice of the Prime Minister. Sarawak's last state election was held in 2001, and elections for the state assembly were not due till 2006.

The elections were held nine months earlier than required by the constitution. The constitution allowed for a parliamentary term of up to five years. Elections were required to be called three months after parliament is dissolved. The government had until the end of November 2004 to call elections.

Candidates were nominated on 13 March, with the National Front winning 15 seats uncontested, and another two seats after the opposing candidates withdrew. The right to withdraw was only introduced as a new rule at these elections. Under this rule candidates are allowed a three-day period to withdraw following nomination day. Of the 17 parliamentary seats won uncontested, nine were in the state of Sabah, six in Sarawak and two in Johor.

PAS won a state assembly seat Senggarang in Johor for the first time, after the National Front candidate was disqualified because she was seconded by someone who was not a registered voter in the constituency that she wanted to contest. The requirement that the seconder be registered in the same constituency was only introduced in 2004. This seat was influenced by other opposition parties to gain many state seat in 2008 contest.