First term

In 2010 he was elected with the program of bringing the local government-owned companies under direct local government control and under full oversight of the assembly. 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. Instead of always choosing between individual developments while the stability of the city is according to him always pressed to the limit, he wants to drive the macroeconomic curves of the city into a long-term self-sustaining.^[9] The Prime Minister guaranteed the city will be provided with the funds necessary for finishing ongoing infrastructure investments.^[10]

Until 2013 the mayor's administration completely overhauled the structure of the companies owned by the local government. In the new structure the companies operate more efficiently, which resulted in significant reduction of operating costs. This money can be redirected to development.

In 2013 Viktor Orbán's government started a program to lift Hungary's local governments out of debt. 100% of the debts of settlements whose population is under 5000 was repaid by the government. 60% of the debt of Budapest was repaid by the government. Later the remaining 40% was also repaid by the government, after the government decided to eliminate all debts of all local governments. In this year the national government accepted the request of the local government to finance the BKISZ project from EU funds. This project builds the sewerage system in all parts of the city that did not have this infrastructure yet. Construction works will finish in Summer of 2015. The capacity of the city's wastewater treatment plants by 2009 had already been increased to be able to treat all generated wastewater.

In 2013 István Tarlós's administration drafted the city's next development plan, that applies to the 2014-2030 time period. 27 large projects were initiated to be realised from EU funds until 2020.^[11] Among them was the complete reconstruction and extension of Metro Line 3, the extension of several tramlines and the purchase of new trams and buses.

From 1 January 2014 the price of most public transport passes for natural persons was decreased by 10%. This was made possible by the reorganized control activity which reduced illegal travel, increased the number of passes sold and the amount of money flowing in from pass sales.^[12] This was the first time since the fall of communism that pass prices became cheaper.

On 28 March 2014, the fourth metro line, which was constructed for eight years, was opened to the public. During Tarlós's term the capital renegotiated the contracts, by which act it was able to regain tens of billions of forints of the total cost of more than 400 billion forints.^[13]

In spring of 2014 a program was initiated to install 300 ticket and pass automats citywide. These automats allow payment both via cash or credit card. The automats operate 24 hours a day, thus provide more flexibility to customers. The automats also made queues at ticket and pass offices shorter.

The municipal government operates approximately 1300 buses daily. By September 2014 500 modern low-floor buses were bought, of which 300 were newly manufactured. This made it possible to scrap 500 of the oldest buses that were both in a bad state and polluted the environment too much. The municipal government plans to serve the public from 2018 only by modern low-floor buses.^[14]

In September 2014 introduction of the FUTÁR information system was completed. It allows the traffic control center to continuously monitor all public transport buses and carriages of the city by having installed GPS in each of them, and it makes communication possible with the drivers concerned, e.g. with all drivers of a specific line, or of all lines affected by an accident on their common route. 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. The central computer system calculates the time remaining until the buses and carriages reach the stops. The boards also inform passengers about temporary route modifications and other special circumstances. The information provided by the boards can also be accessed via internet, a smartphone application is also available to do this. In September 2014 the MOL Bubi bicycle hire system was opened for public use. It consists of 76 stations in the inner part of the city, which serve 1100 bicycles.^[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.^[17] As prescribed by another contract signed on 8 October 2014, by 2017 a modern electronic ticket and pass system will replace the current and outdated paper-based system.^[18] The system is going to be introduced in multiple phases.

Second term

Tarlós was re-elected mayor for a second term (which this time was five years long) in the 2014 election. He received 49.06% of the votes.^[19]

The reconstruction of tramlines 1 and 3 was finished in this term. These lines run along two beltways at the border of the inner part of the city. The reconstruction eliminated the speed limits that had to be introduced because of poor condition of the tracks.^[20] In this term the Interweaving Tramlines Project of Buda (Budai Fonódó Villamos Project) was also completed. This project unified the tramlines of the Buda (western) side of the Capital, creating lines that enable travelling from the northern areas of the city to the southern areas, without the need to transfer from one line to another.^[21]

On 11 November 2014 a contract was signed according to which 200 new low-floor buses entered service in 2015. This increased the ratio of low-floor buses in the bus fleet of the city from 55% to 70%.^[22] The municipal government announced in June 2017 that the ratio of low-floor buses reaches 95-99% by September 2017.^[23]

The first train of Metro Line 3 was handed over in January 2016 to the Russian Metrowagonmash (the original manufacturer) to be reconstructed.^[24] Tarlós had preferred buying new trains, but he had been overwritten by the Orbán government.^[25] The prototype of the reconstructed trains entered service on 20 March 2017.^[26] Since then, the number of reconstructed trains serving the line is scheduled to increase by 2 trains every month.

On 4 September 2017 the contracts for reconstructing the whole tunnel of Metro Line 3 and the stations of the northern section were signed, thus the reconstruction effectively started. The stations will be finished by 31 December 2018. After this phase, the stations of the middle and southern sections will be reconstructed, the order of these two phases is not yet decided. Overhauling the tunnel is set to end by 24 August 2020.^[27]

In June 2015, Budapest decided to bid for the 2024 Summer Olympics. Tarlós emphasized the necessary city development projects and the expected boom in tourism.^[28] However, in January 2017 a civil organization called Momentum Movement started a petition to have a referendum for Budapest residents whether they want to organize it or not. The Movement campaigned for redirecting the funds from a high-risk investment to immediately support health care and education.^[29] On 17 February 2017, it was announced that 266,151 signatures had been collected,^[30] to which Tarlós reacted by negotiating with PM Viktor Orbán and the Hungarian Olympic Committee, then agreeing to and withdrawing the bid to host the 2024 Summer Olympics, leaving only Los Angeles and Paris in the race. Tarlós blamed the opposition parties they were "backing out" from their earlier position of supporting the bid, and called this attitude as "treachery".^[31]

On 5 February 2018, nine opposition parties started collecting signatures to hold a referendum to ensure all 20 stations of Metro Line 3 are made fully accessible during the line's reconstruction.^[32] Until that point, the local government only planned to guarantee this at 12 stations, but on 7 February the mayor's office negotiated with the national umbrella organization for disabled people, then announced it would build inclined elevators next to the existing escalators at 6 more stations.^[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. Tarlós and Orbán also accepted a 10-year "Budapest 2030" urban development plan. The government guaranteed the functions of garbage disposal and sewerage remained the responsibility of the local municipality.^[37] In June 2019, in the opposition's first primary election, Gergely Karácsony was elected as the united opposition's joint candidate to the position of mayor.^[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.^[39] After his defeat, Tarlós announced his retirement from politics and did not take over his gained seat in the General Assembly.^[40]