[10][11] As the winner of the 2021 opposition primary, he was the candidate of the United for Hungary challenging Prime Minister Viktor Orbán in the 2022 parliamentary election, which he lost.

[12] Márki-Zay was born in Hódmezővásárhely, in the Hungarian People's Republic, on 9 May 1972, to a mother who was a chemist and a father who was a physics teacher.

[14] Between 1996 and 2004, Márki-Zay first worked at DÉMÁSZ, which was at the time responsible for supplying electricity to Southern Hungary, then at Kontavill-Legrand as an economist and marketing manager.

[19] Márki-Zay said that he did not sympathise with the views of any of the parties supporting him, describing himself as a right-wing Christian, and a disappointed Fidesz voter.

[20] Despite the historically unprecedented unity of the opposition parties backing him, his candidacy was initially seen as a long-shot by many observers, owing to Fidesz's popularity in the city,[21] as well as Márki-Zay's political inexperience.

[26] In 2018, he founded the non-partisan Everybody's Hungary Movement (Mindenki Magyarországa Mozgalom; MMM) in order to further cooperation between opposition parties,[27] and to support representative democracy.

He was fined for libel on multiple occasions[31][32] and ordered to remove a "migrant counter" he placed inside the city hall.

[33] In 2019, Márki-Zay ran for reelection, this time under the banner of MMM, as well as the Organisation for a Clean Vásárhely (Tiszta Vásárhelyért Egyesület).

He defeated the Fidesz-backed independent candidate István Grezsa by 13,478 votes to 10,042, earning him a second term as the city's mayor.

[43] On societal issues, he attacks Viktor Orbán for his measures, which he considers to be liberticidal, labeling some of his government's actions xenophobic and homophobic, like the 2022 Hungarian LGBTQ in education referendum, and has been described as supporting LGBT rights.

[44][42] He accused the Prime Minister of "organizing immigration" and said that it was "in Fidesz", the ruling party, "that we find the most gay people", suggesting that Orbán's son shared this sexual orientation.

"[47] Perceived as a neoliberal on economic issues, he opposes raising the minimum wage, believing that the market would be able to regulate salaries, and reforming the tax system.

[20][3][51] The family considers itself practicing Roman Catholic, even though Márki-Zay is at odds with dogmatic Church teachings on marriage and abortion.