Mak was selected as the Conservative Party candidate for Havant for the 2015 general election. His selection was met with considerable opposition by Tory members on the grassroots website ConservativeHome, with accusations of incompetence and his "parachuting" in, as an A-List candidate with no local connections to the safe seat. The Havant Conservative Association responded to these comments by pointing out that only 20 of the 96 applicants for the shortlist were local people. It is alleged that Mak has still not moved his permanent residence to Havant and remains registered to vote elsewhere. During the election campaign it was alleged by the rival UKIP candidate that Mak had falsified his CV, presented to the local Conservative Association during the open primary in which he was selected as the Conservative candidate for Havant. The allegations were that Mak had falsified endorsements from The Daily Telegraph and Conservative Home, exaggerated his business success, and misrepresenting his electoral performance in the 2014 Tower Hamlets London Borough Council election. In the week following allegations about Mak's CV, the local press reported that a claim in his campaign literature—that he regularly attends St Faith's Church, Havant—had been repudiated by the church rector; a spokesman for the Diocese of Portsmouth confirmed that Mak had only been seen in the congregation for the installation of Fr Tom Kennar, in February 2015, over two months prior to the leaflet's publication. Mak was elected as Member of Parliament for Havant at the 2015 general election. He is the first person of Chinese origin to be elected to the House of Commons. However, he is uncomfortable with being defined solely by his ethnic identity and has dismissed the notion that his election as MP would raise the profile of British East Asians. In an interview with the South China Morning Posts Post Magazine, he said "If the CFC and Chinese for Labour think I am going to be representing every Chinese, Thai, Vietnamese and Korean—and there are many in my constituency—they are mistaken. It's a stupid story. I am not standing for the Chinese population of Britain. I am standing for the people of Havant and my country". Following his election he expressed concern about the attention his ethnicity, and subsequent political breakthrough, was receiving from both international media and British Chinese groups.
Backbencher
In June 2015, Patrick Kidd wrote in The Times that Mak had gained a reputation for "self-promotion" amongst his parliamentary colleagues and "is getting up people’s noses". It was also reported in The Spectator that Mak was prevented by Conservative MPs from sitting in his "favourite spot" behind David Cameron at Prime Minister's Questions, which Mak had hoped would enable "a brief TV appearance". Despite positioning himself as a eurosceptic during Havant Conservative Association's process to select their prospective parliamentary candidate, and writing before the 2015 election that, "we shouldn’t be afraid to leave ", Mak announced in February 2016 that he would campaign to remain in the EU in the June 2016 EU membership referendum. This decision was criticised by local party members as a political "U-turn" and received speculation in The Huffington Post as being affected by "careerism." In June 2017, following the result of the 2017 general election, Mak was mocked by BBC presenter Simon McCoy due to his repetition of soundbites defending Theresa May. McCoy asked: "Is this a speech you have all been given to read out?" in response to Mak stating: "Our job is to make sure we form a strong and stable government" and to "provide certainty".
