The vote was called to resolve a political stalemate between historical rivals DUP and Sinn Fein, who will now have to begin negotiations to govern together under a power-sharing agreement struck to bring an end to civil strife in the British-ruled province.
Final results from Thursday's regional elections showed the DUP had won 28 seats and Sinn Fein 27 in the province's semi-autonomous 90-seat parliament after all ballots were counted on Saturday.
The Social Democratic and Labour Party (SDLP) won 12 seats, the Ulster Unionist Party 10, the Alliance Party of Northern Ireland (APNI) eight and others five.
The result means pro-British unionist parties will no longer command a majority leadership for the first time since the province was created in 1921.
The DUP and Sinn Fein have jointly governed Northern Ireland following a 1998 peace deal that brought an end to three decades of violence - a period known as The Troubles - in which more than 3,500 people were killed.
The election energised voters, with turnout at 64.8 percent - the highest since the first vote after the 1998 accord known as the Good Friday Agreement.
Exacerbated by the Brexit vote, in which the DUP backed leaving the EU while Sinn Fein campaigned to stay, tensions between the two boiled over in January when Sinn Fein collapsed the government by withdrawing.
If Sinn Fein still refuse to work with the DUP's leader Arlene Foster, who was Northern Ireland's first minister, then the assembly could be suspended and the province fully governed from London.
Foster spoke of "challenging" results and conceded to Sky News that it "looks like it has been a very good day for Sinn Fein".
It was a disastrous night for the Ulster Unionists, whose haul of 10 seats led to the resignation of leader Mike Nesbitt, who said the "buck stops here".
Members of the public look out from a Sinn Fein information booth. Source: AAP
Sinn Fein buoyant
The election was triggered when Sinn Fein's Martin McGuinness quit as deputy first minister over a costly, bungled green energy subsidy scheme rolled out by first minister Foster when she was economy minister.
Sinn Fein wanted her to step aside during an investigation and say they will not enter government if the DUP nominates her to become first minister again.
Michelle O'Neill, who took over from the retiring McGuinness as Sinn Fein's leader in Northern Ireland, told AFP she was willing to find "a way forward" with the DUP.
The parties have three weeks to strike some sort of deal, otherwise the Belfast legislature is likely to be suspended and its powers returned to London.
"After a brutal and divisive campaign there is no real expectation that the institutions will be up and running in the next few weeks," The Irish News newspaper said in an editorial.
Brexit factor
Besides the energy scheme scandal, old wounds between the two communities were also reopened by the United Kingdom's vote in June to leave the European Union.
Northern Ireland voted to stay in the EU but was overruled by a majority vote to leave in Britain as a whole.
Britain has signalled its intention to leave the EU's customs union after Brexit, raising fears of a new hard border between Northern Ireland and the Republic of Ireland, which will remain in the EU.
London, Dublin and Brussels have all insisted they want to keep free movement across the Irish border - an arrangement dating from its creation in the 1920s.
But the possibility of a return to checkpoints has stirred memories of The Troubles when cross-border smuggling was rife and British outposts along the frontier became targets for militants.
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