* PM Orban's party has strong lead in parliamentary vote
* Far-right Jobbik backed by one in five Hungarian voters
* Investors concerned over PM's go-it-alone policies
Orban has clashed repeatedly with the European Union and foreign investors over his maverick policies, and after Sunday's win, big businesses were bracing for another term of unpredictable and, for some of them, hostile measures.
But many Hungarians see Orban, a 50-year-old former dissident against Communist rule, as a champion of national interests. They also like the fact that under his government personal income tax and household power bills have fallen.
After 71 percent of the ballots were counted, election officials projected Orban's Fidesz party would win 135 of the 199 seats in parliament - passing the two-thirds threshold needed for his party to unilaterally change the consitution.
The same projection gave the Socialist-led leftist alliance 39 seats, while Jobbik would take 25 seats.
"We can now say for certain that for the first time since the change of regime, a centre-right government will govern for two successive terms," said Fidesz lawmaker Gergely Gulyas, referring to the collapse of Communist rule in 1989.
The result for Jobbik will be watched closely for clues about how other nationalist right-wing parties, such as France's Front National, will perform in European Parliament elections next month.
In terms of the share of the national vote on party lists, Jobbik won 21.25 percent, against 24.9 for the second-placed leftists, according to the incomplete results. Jobbik picked up a 15.86 percent share of votes four years ago.
Sunday's result as it stands now was the strongest showing in the past few years for any far-right party in the European Union, said Cas Mudde, Assistant Professor at the School for Public and International Affairs at the University of Georgia.
He said the only far-right party on the continent that has performed better was Switzerland's People's Party which had 26.6 percent of the vote. Switzerland is not an EU member.
Jobbik has pledged to create jobs, be tough on crime, renegotiate state debt and hold a referendum on EU membership. While it denies being racist, it provides a lightning rod for suspicion among some Hungarians towards the Roma and Jews.
"I'm sure we'll surprise everyone," Jobbik leader Gabor Vona said in his home town of Gyongyos earlier on Sunday after casting his vote accompanied by his wife and son.
In the past four years, Orban's policies have included a nationalisation of private pension funds, swingeing "crisis taxes" on big business, and a relief scheme for mortgage holders for which the banks, mostly foreign-owned, had to pay.
Orban has pledged more of the same if re-elected, and the business community expects him in particular to press ahead with a plan to transfer big chunks of the banking sector into Hungarian hands, and impose more levies on foreign power firms.
More unpredictable policies could weigh on Hungary's forint currency, especially if the central bank - led by a close ally of Orban's - cuts interest rates further from record lows, against a backdrop of jittery sentiment in global markets.
Those policies have played well with voters and helped Hungary emerge from recession, but some economists say that by hurting foreign investors, Orban may have scared off the kind of investment Hungary needs for long-term growth.
"Big business do not want the frequent changes of policy, particularly in terms of taxes, which were characteristic of Orban's last term," said Timothy Ash of Standard Bank.
The election was likely to be a new low point for the leftists, who were ousted in 2010 after racking up huge amounts of public debt, and after their leader four years earlier was caught on tape admitting his government was lying to the public.
Some Hungarians worry that, without a credible challenge to his dominance, Orban has accumulated too much power.
Critics say Orban has already used his mandate to curb democratic checks and balances and the freedom of the media, allegations his government rejects.
"We had a regime change in 1989 so we don't have to put up with a one-party system any longer, and these four years looked a lot like a one-party system," Agota Guczky said in the town of Veresegyhaz just east of Budapest.