Early membership with UMNO

In 2000, he joined UMNO, becoming Kota Bharu UMNO division chief a year later. He was later suspended but became Kelantan Umno deputy lion chief two years later. Zaid contested and won the Parliamentary seat of Kota Bharu in the 2004 general election.^[5] However, UMNO dropped him as a candidate in the 2008 general election. It suffered heavy losses, including the 2/3 majority necessary in the Dewan Rakyat to pass amendments to the Constitution.

Zaid is known for his criticism of the government's handling of legal issues such as the judiciary, human rights and Islamic law. He supported the establishment of the Royal Commission of Inquiry into the Lingam Video Clip, criticising the government's initial response to the clip.^[6]

2008: Resignation from the Cabinet

After criticising the arrests of three prominent individuals—Democratic Action Party MP Teresa Kok, blogger Raja Petra Kamaruddin, and journalist Tan Hoon Cheng—under the Internal Security Act, Zaid resigned from the Cabinet on 15 September 2008.^[9]

Zaid Ibrahim urged the Yang di-Pertuan Agong not to appoint Najib Razak as Prime Minister of Malaysia, and instead appoint someone else from UMNO. He pointed out Najib has been linked on the internet and by political rivals to the brutal murder of Altantuya Shaariibuu. Zaid also cited the RM400 million in commissions reportedly paid by the Defence Ministry while Najib was minister for the procurement of submarines, and pointed out that Abdul Razak Baginda, Najib's friend, was an agent in the deal.^[10] This was after Mahathir Mohamad, the former Prime Minister also said that Najib did not shine as a deputy prime minister and stated that Najib carried a lot of baggage into the Prime Minister's job.^[11]

2009-2010: Joining Parti Keadilan Rakyat

In June 2009 Zaid joined the opposition Parti Keadilan Rakyat (PKR).^[12] As part of the Pakatan Rakyat opposition alliance, Zaid was appointed to head the coalition's Common Policy Framework group where he was responsible for formulating a common manifesto and governing policy between the three disparate political parties (PKR, PAS, DAP) that made up the loose opposition alliance.^[13][14] He also headed efforts, in his role as Pakatan coordinator and pro-tem committee chairman of Pakatan Rakyat Malaysia, to register Pakatan Rakyat as an official political coalition party with Malaysia's Registrar of Societies on 3 November 2009.^[15][16] During the Hulu Selangor by-election in April 2010, Zaid was also fielded as the PKR candidate, but was narrowly defeated by P. Kamalanathan of the Malaysian Indian Congress.^[17]

In the 2010 PKR party elections, Zaid Ibrahim contested for the party post of Deputy President after having received over 30 nominations. He confirmed his candidacy in a posting on his blog on 16 October 2010.^[18] However, in Nov 2010, Zaid Ibrahim withdrew his candidacy as a sign of protest against serious allegations of fraud and electoral misconduct perpetrated in the PKR party elections by his opponent, the PKR establishment candidate Azmin Ali.^[19][20] He subsequently resigned from the party, citing his loss of confidence in the PKR party leadership for their involvement in the electoral fraud of the 2010 party elections.^[21][22]

2010-2012: Founding KITA

On 13 December 2010, the Malaysian Human's Justice Front (AKIM), a tiny Kelantan-based opposition party, announced that Zaid Ibrahim has joined its ranks as a party member, with the view of having Zaid lead and revamp AKIM into a viable political party for the coming 13th Malaysian General Elections.^[23] The party further explained that Zaid had submitted his membership application to join AKIM in Nov 2010 after his former party, PKR, accepted Zaid's resignation.

During the party's annual general meeting on 15 December 2010, Zaid Ibrahim was elected as the party's new president, taking over from Zakaria Salleh, the outgoing president of AKIM.^[24] The party also announced that it had adopted a new name, the People's Welfare Party or Parti Kesejahteraan Insan Tanah Air (KITA).^[25] Zaid Ibrahim also announced that KITA would be a multi-racial democratic party open to all races in Malaysia, and despite its current small size, aims to make an impact in the country's political scene by focusing on goals for the long haul.^[26] Zaid also unveiled the KITA's official party ideology and principles, including its new constitution, manifesto, and logo, in Kuala Lumpur on 19 January 2011. Zaid resigned as KITA chief in 2012.^[27]

2012-2017: Becoming an Independent

In 2014, after stating that the lack of religious discourse by the religious leaders in Malaysia that does not allow for different interpretations of Islam promotes extremism and makes Malaysia similar to the Islamic State of Iraq and Syria, he was criticised by Islamic scholar Fathul Bari Mat Jahya for being a liberal who only wanted to follow civil laws and not those created by Allah and that it is the responsibility of the Ulema to specifically identify what is wajib (obligatory), halal (allowed), and haram (prohibited).^[28]

2017-2020: Joining Democratic Action Party

In 2017, Zaid had announced in a press conference in his Petaling Jaya home that he has officially joined the Democratic Action Party, reasoning that "he will be able to reach out to Malay voters".^[29]

On 20 April 2020, Zaid had announced he leave DAP.^[30]

On 20 October 2020, Zaid is no longer Kelantan DAP Chairman. He said "Many still describe me as Kelantan DAP chief. It's no longer true,...".^[31]

2022-present: Returning To UMNO

In August 2022, Zaid Ibrahim return to UMNO. He said "I want UMNO because I feel that they can provide that solidarity. They can provide that energy and the strength to bring everybody else on board and institute real reform in this country..."^[32]

On 16 September 2022, Zaid rejoins UMNO. He said he wants to reform the party from “within”.^[33]

On 14 June 2023, Zaid has called on Prime Minister Anwar Ibrahim to release former Prime Minister Najib Razak "in the interest of the people." He argues that in the grand scheme of things, the RM42 million (the amount of corruption for which Najib is imprisoned) is a relatively minor issue.^[34]