It has done so with the backing of some left-wing and liberal parties in what some observers feel marks a hammer blow to a long-standing pro-EU consensus in the country.
The development, which comes after repeat voting in four polling stations (out of 8500 nationwide), will make little significant difference to the parliamentary standings and Prime Minister Aleksandar Vučić's government will retain a majority of seats.
In the national vote on 24 April, there were accusations that voting was rigged to keep the Dveri and Democratic Party of Serbia parties out of Parliament.
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The Dveri-DSS coalition recorded 4.99 per cent of the general election, a single vote short of the five per cent threshold needed for parliamentary representation.
This sparked protests, despite an OSCE monitoring team declaring there were no major irregularities, and Bojan Pajtic, leader of the center-left Democratic Party, traditionally supportive of EU accession, urged supporters to vote for Dveri-DSS in the recount.
Several other left and centre-left leaders did the same and, after the partial recount, the alliance gained 13 seats.
The DSS was once a moderate pro-European conservative party and part of the anti-Milošević movement, but is now headed by Sanda Rašković Ivić, known as Serbia's Marine Le Pen and opposed to Serbia joining the EU, while Dveri is an openly homophobic movement.
The ultra-nationalist and pro-Russian Serbian Radical Party, led by Vojislav Šešelj, recently acquitted of war crimes by the Hague Tribunal and a one-time Vučić patron, not only re-entered Parliament, but is set to be the main opposition party with 21 seats.
That, it is argued, gives the Radicals a parliamentary platform for rhetoric "inveighing against the EU and Serbia's neighbours."
These sorts of parties are on the rise across much of Europe and the party's presence "will create a charged atmosphere" similar to that of the troubled 1990s, said Tibor Jóna, a Serbian commentator.
Matteo Bonomi, of the Brussels-based European Policy Centre, suggests that the return of anti-EU and pro-Russian forces in the Parliament might signal that the country's path towards EU membership will become "a bit more complicated."
He argues that the results of the vote "reveal a fickle and fragmented Serbian society and political class when it comes to the country's EU orientation, and that Vučić will have to work hard to prove his European and democratic credentials against this backdrop."
Pajtic's urging supporters to vote for the Dveri-DSS coalition came as a shock to many who had supported his party, including Serbian theatre director Kokan Mladenovic who said, "I don't believe we should make pacts with the devil, no matter the price. I don't believe we should radically change our own beliefs just in order to help a certain opposition party."
Serbia's Gay Straight Alliance (GSA) also called on voters to ignore Pajtic and not vote for Dveri-DSS, which it says is openly homophobic.
Pajtic's coalition partner, Zoran Zivkovic, president of the New Party, also refused to support Dveri-DSS, which promotes closer relations with Russia, support for the annexation of Crimea and membership in the Russia-sponsored Eurasian Economic Union.
Pro-EU activists are reportedly said to be shocked that a formerly sympathetic leader of the Democratic Party (Pajtic) could switch allegiance for allegedly "opportunistic reasons."
Opponents of the Serbian government's pro-Europe policies will now have a total 35 seats in the 250-seat Parliament, having failed to win any seats in the last elections in 2014.
Even so, Vučić dismissed the Dveri-DSS entry into Parliament, saying, "It looks like they will pass the threshold, so there is a parliamentary restaurant and a paycheck for them. But what I will not allow them to do is to destroy Serbia, the state, its stability and fragile democracy."