At the previous parliamentary election, in April 2014, the incumbent government — composed of Fidesz and its satellite ally the Christian Democratic People's Party (KDNP) — was able to achieve a two-thirds majority for the second consecutive time with 44.87 percent of the votes. According to their critics, this overwhelming proportion was only because of the new election law (mostly due the introduction of compensation votes also for the individual winners) which was adopted by the ruling coalition in 2011. In early 2015, however, Fidesz lost its two-third majority following the 2014 Hungarian Internet tax protests and subsequent decrease in support for the government. The governing party suffered defeats at two parliamentary by-elections in February and April 2015, both in Veszprém County.
The left-wing electoral alliance Unity, which failed to win the 2014 national election after its five constituent parties gained a total of only 38 seats, broke up shortly thereafter. Its former member parties (MSZP, Együtt–PM and DK) participated in the May 2014 European Parliament election individually, while the MLP did not participate in the election at all. Due to this fragmentation of the left-wing opposition, the radical nationalist Jobbik became the second largest party in a nationwide election for the first time since its establishment. The PM broke off the permanent nature of its alliance with Együtt on 9 November 2014.
After a few months of crisis for Fidesz from November 2014, which was marked by internal conflicts (e.g. businessman Lajos Simicska's fall from grace within Fidesz) and corruption allegations, the governing party regained much of its lost support during the European migrant crisis during the summer of 2015, when Prime Minister Viktor Orbán announced the construction of a 4-metre-high (13 ft), 175-kilometre-long (109 mi) fence along its southern border with Serbia. The Hungarian government also criticised the official European Union policy for not dissuading migrants from entering Europe. The barrier became successful, as from 17 October 2015 onward, thousands of migrants were diverted daily to Slovenia instead.
On 13 December 2015, the 26th congress of the ruling Fidesz re-elected Viktor Orbán as party leader. Orbán said in his speech that he was ready to lead the party into the forthcoming parliamentary election and to continue to serve as prime minister if Fidesz won re-election in 2018. With that statement, Orbán made clear that he did not intend to become President of Hungary in succession to János Áder during the 2017 indirect presidential election.
On 2 October 2017, the elected leader of the MSZP, László Botka, announced his withdrawal, saying that he thought some of the Hungarian opposition did not care about changing government.
Orbán and Fidesz's strength going into the election came into question when the party unexpectedly lost a mayoral by-election in Hódmezővásárhely, considered a Fidesz stronghold, on 25 February 2018, to an independent candidate supported by every opposition party. Election observers and critics of Orbán speculated whether Hungary's opposition parties could create a similar alliance on the national level, though the opposition parties had been unable to create a common strategy by late March 2018. Orbán increased his efforts as a result of this loss.
According to observers prior to the election, winning re-election was seen as more difficult for Orbán than expected.