Since 2006, he was the Chairman of the Fidesz–Christian Democratic People's Party (KDNP) Fraction-Alliance in the General Assembly of the Municipality of Budapest, and served as the political leader of the initiative "Social Referendum 2008".

Both his father, Dr. István Tarlós, Sr., a lawyer, and his mother, Hilda Dienes, a chief accountant, worked for the Hungarian Academy of Sciences.

[3][4] Tarlós attended the Technical University in Budapest, eventually receiving a diploma in civil engineering.

[7] He left SZDSZ, which formed a coalition with the Hungarian Socialist Party (MSZP), because of ideological and moral differences in the summer of 1994.

Tarlós could not accept the radical change in directions and principles of the party within the short period of its existence.

The remains of the first conservative party of Prime Minister József Antall of the Hungarian Democratic Forum (MDF) considered Tarlós's Budapest mayoral candidacy controversial; this resulted in numerous secessions of own party members and leaders as well as demonstrations on the streets of District III and within the town walls.

He pledged to divert more funds to material and salary expenditures of services (police, firefighters, schools, public transport) the state of which he described as neglected.

[9] The Prime Minister guaranteed the city will be provided with the funds necessary for finishing ongoing infrastructure investments.

In 2013 István Tarlós's administration drafted the city's next development plan, that applies to the 2014-2030 time period.

FUTÁR also provides information to passengers: 263 digital boards were installed to high-traffic bus and tram stops.

[15] These boards show the approximate time that remains until the next buses and carriages of the different lines arrive to the stop.

[16] The city was scheduled to receive 47 completely low-floor CAF trams in 2015 and 2016 according to a contract signed on 2014 March 5.

The Movement campaigned for redirecting the funds from a high-risk investment to immediately support health care and education.

Tarlós blamed the opposition parties they were "backing out" from their earlier position of supporting the bid, and called this attitude as "treachery".

[33] Both the opposition parties and the umbrella organization operating independently from them announced they regard acceptable only full compliance with accessibility standards at all stations.

On 21 February, initiator of the referendum Csaba Horváth (socialist floor leader of the Municipal Assembly) cancelled the signature collecting, referring to the Mayor's former announcement and to the calculations regarding the cost of the referendum can cover the cost of building elevators at the two remaining stations.

[34] On 10 October 2018, István Tarlós announced that he would run for a third term as Mayor of Budapest, after negotiating about his future role with Prime Minister Viktor Orbán.

[35][36] According to the press, the two politicians concluded a 15-point agreement, which contained altogether HUF 1,000 billion development package.

The Metropolitan Public Development Council was established with members delegated by both the government and the General Assembly of Budapest.

The government guaranteed the functions of garbage disposal and sewerage remained the responsibility of the local municipality.

[38] In the October 2019 local election, Tarlós, receiving 44.10% of the vote, was defeated by Karácsony, while the opposition parties also gained majority in the General Assembly of Budapest.

[40] Weeks after his defeat during the 2019 local elections, István Tarlós was appointed Prime Ministerial Commissioner for the Development of National Transportation and Public Service Infrastructure on 31 October 2019.

Additionally Tarlós was given the task of the honorary chairman of the Disaster-Recovery and Civil Protection Council as well as of the Braunhaxler Association of Budapest District III.

During that broadcast, a casual mention was made by Sullivan of the need to send aid to Hungarian refugees fleeing from the effects of the Soviet invasion.