[13] Wickremesinghe received an honorary doctorate from Deakin University in Australia on 14 February 2017 for his significant contributions in reforms in economy, education and human rights.

[24][25] It further stated that Wickremesinghe held "unauthorised meetings of police officers involved in counter-insurgency operations in the housing complex, and that as such, he had abused his authority".

Wickremesinghe was defeated in the race for Opposition Leader by two votes by fellow UNP member Gamini Dissanayake, who had re-joined the party.

President Chandrika Kumaratunga also chaired cabinet meetings as de facto head, but her influence over decision making was strictly limited.

The agreement was signed on 22 February 2002 at different locations in the war zone by both parties and the Norwegian Ambassador to Sri Lanka Jon Westborg acted as the facilitator.

In this statement, it was stated that "both parties have decided to explore a political solution founded on internal self-determination based on a federal structure within a united Sri Lanka".

[55][56][57] Analysts saw Wickremesinghe was fanning the internecine feuds among the Tigers and systematically weakening them and a foreign policy intended to tighten the global dragnet against the LTTE.

[61] They continuously criticized and protested against the CFA claiming it as a threat to the sovereignty of the country which would ultimately lead the way to the formation of a separate state for the LTTE, or Tamil Eelam.

[64] A few days after LTTE proposed the Interim Self Governing Authority (ISGA), President Chandrika Kumaratunga sacked three ministers of the cabinet and took over the ministries using her constitutional powers, ending the uneasy coalition between her and Wickremesinghe while he was out of the country.

Despite the expectation of a full six-year term, and planned projects cut short by the defeat, the UNP was optimistic that it could regain power in a future election.

Sirisena, Mahinda Wijesekara, Naween Dissanayake, Hemakumara Nanayakkara, R. M. Dharmadasa Banda, Neomal Perera and Chandrasiri Sooriyaarachchi.

[72][73] The defection of the party stalwarts to join the government continued thereafter with several members such as; Susantha Punchinilame, Mahinda Ratnatilaka, Nandimithra Ekanayake, Thilanga Sumathipala, R. Duminda Silva, Ravindra Randeniya and Ashoka Wadigamangawa.

[90][91] Wickremesinghe signed an Alliance Agreement with twelve other opposition parties in November 2009 and he announced that a common candidate would be fielded for the presidential election which would be held in 2010.

[97][98] Wickremesinghe's UNP-led UNFGG won the 2015 parliamentary elections held on 17 August 2015, thus he was officially inaugurated as the Prime Minister for a fourth time, with 106 seats in the 225-member Parliament (though short of 7 seats to secure the simple majority of the Parliament) defeating the political rivalry UPFA leader and former President Mahinda Rajapaksa in his bid to return as prime minister after his defeat as president.

[101] He also took steps to develop the former war-zones by touring the affected areas and met civil activists to discuss the issues faced by the Jaffna civilians and schools and to expedite investigations of missing persons.

[109] Wickremesinghe also organized the Sri Lanka Economic Forum 2016 with the presence of international investor and Founder Chairman of Open Society George Soros and Nobel Laureate Economist Joseph Stiglitz and many other experts such as Ricardo Hausmann.

[125][126][127] On the evening of 26 October 2018, President Maithripala Sirisena appointed Mahinda Rajapaksa as prime minister after the United People's Freedom Alliance withdrew from the unity government.

[138][140] The issuing of ten times the advertised bonds, and at a higher than expected rate, was alleged to cost the Sri Lankan government an additional Rs.

[146][147][148][149] Perpetual Treasuries was one of the primary dealers in the sale and is owned by son-in-law of the Governor of the Central Bank of Sri Lanka Arjuna Mahendran, who was appointed by Wickremesinghe.

[139][150][151] On 28 October 2016 the Committee On Public Enterprises, after a lengthy investigation, found Mahendran responsible for the bond issue scam and recommended legal action be taken against him.

On 15 March 2018 Colombo Fort Magistrate's Court issued an arrest warrant on Arjuna Mahendra on charges of criminal breach of trust for allegedly providing confidential information of the Central Bank of Sri Lanka to Perpetual Treasuries Limited.

[161] On 9 July, the Prime Minister's office announced that Wickremesinghe was ready to resign to make way for an all-party government as protesters stormed and burned his residence that day.

[165] Following Rajapaksa's official resignation, Wickremesinghe was sworn in as the acting president of Sri Lanka before Chief Justice Jayantha Jayasuriya on 15 July.

[7][8] On 21 July, he was sworn in as the ninth (eighth executive) President of Sri Lanka at the Parliament premises before Chief Justice Jayantha Jayasuriya.

[169] In September 2022, Wickremesinghe visited the UK as the head of state to attend the funeral of Queen Elizabeth II, at the invitation of King Charles III.

[172] Security forces raided the protest site in Galle Face Green in the early hours of 22 July, a day after Wickremesinghe was sworn in.

Wickremesinghe was criticized for hosting celebrations of the 75th anniversary of Sri Lankan independence on 4 February 2023, while the country was amidst an economic crisis.

[176] Under the IMF program, his administration initiated a number of economic reforms including enforcing cost reflective pricing for state owned Ceylon Electricity Board (CEB)[177] and Ceylon Petroleum Corporation (CPC),[178] enacting the Central Bank (CB) Act of Sri Lanka to give freedom to the Central Bank of Sri Lanka in its decision making,[179] enacting several other key economic bills such as Economic Transformation Bill,[180][181][182] and improving the relationship with Japan which soured under Gotabaya Rajapaksa over the cancellation of the LRT project.

[185] In August 2024, the Supreme Court delivered a landmark judgement which held that Wickremesinghe as the Minister of Finance, former Chairman and members of the Election Commission and the Attorney General, violated the fundamental rights guaranteed under the Sri Lankan Constitution of Dr Harini Amarasuriya, MP of the National People's Power; Ranjith Madduma Bandara, General Secretary of the Samagi Jana Balawegaya; and the Centre for Policy Alternatives and People’s Action for Free and Fair Elections (PAFFREL); by arbitrary and unlawful conduct which led to the 2023 local government elections not taking place at the time that they should have been held.

Following the electoral defeat, UNP deputy leader Ruwan Wijewardena stated that Wickramasinghe won’t contest the upcoming parliamentary election.