Italian far-right party the League, which is vying for the right to form a government after inconclusive elections, drew encouragement from Orban's victory, reprising his line against elite Hungarian-born tycoon George Soros.
The holder of the EU's rotating presidency, Bulgarian Prime Minister Boyko Borisov, also appealed for Hungary's cooperation.
Borissov, in his message to Orbán, said: "I highly appreciate the friendly relations between Bulgaria and Hungary and I am confident of the excellent prospects for the development of fruitful co-operation in bilateral, regional and multilateral terms".
"Migration is like rust that slowly but surely would consume Hungary", Orban had said at one of his rallies, according to BBC.
Orban's government has already attracted controversy for what critics call its erosion of media and judicial independence, as well as its crackdown on civil society organisations, in particular those linked to liberal Hungarian-born USA billionaire George Soros.
Critics said they feared Orban will use his third consecutive term and the Fidesz party's two-thirds control of Hungary's national legislature to intensify his attacks on migration and to strengthen his command of the country's centralized power structure.
The vote - easily the most consequential since Hungary's post-communist transition - was widely seen as a reflection on the state of democracy and the rule of law in a European Union member state that in recent years has been sliding toward autocracy.
German Chancellor Angela Merkel congratulated Orban, a German government spokesman said, adding that she would work with his new government despite differences on migration. "[The opposition's] task is to win power and implement the grand plan: to break Hungary, which stands in the path of immigrants".
Decapitated body of abducted Hajin youth recovered
Moreover, reports suggest that a local terrorist, Mohommad Saleem Parrey has a major role in killing the 24-year-old. So far, police have identified the militants as - Abu Muslim, Hubaib, Khalid, Abu Hamza and Haider.
In Orban-era Hungary, everything revolves around the principle of the ethnically-determined nation: from family and media policy to foreign policy, it's Hungary and Hungarians first.
Orban accuses Soros and the organisations he funds of promoting mass Muslim and African immigration into Europe in order to undermine its Christian identity.
Orban's Fidesz Party won a landslide third-term victory in Sunday's election.
Leaders of Jobbik, the Socialists and several smaller liberal parties resigned after the resounding defeat for the opposition.
He seized the moment when on January 12 2015, months before the peak of the migration crisis in Europe, he said immigration into Europe should be largely halted after Paris attacks launched by Islamist extremists, who were born in France to immigrant families.
In the capital Budapest, where Fidesz won only six out of 18 voting districts, some were disappointed on Monday morning.
"It's a confirmation of Central Europe's emancipation policy", Szymanski told the private TVN-24 broadcaster when asked what Orban's victory means for the EU. Hungary's adamant refusal to accept immigrants or refugees is popular in Hungary, where these election results show that the government bombast, echoed in the state-loyal media, finds resonance.
In Italy, Matteo Salvini, whose center-right alliance is the biggest bloc after inconclusive March 4 elections, was one of the first populist leaders to applaud Orban. "Jobbik is now the second party in parliament, but they couldn't do any better than four years ago", he said. "I think he's just going to push it further and he's not going to be scared off, perhaps, by the increasing tension between... other European countries and Hungary", the MP said.