The moderate forces that led Northern Ireland's first power-sharing government from 1999 to 2002, the Ulster Unionists and the Catholic-backed Social Democratic and Labour Party, won 10 and 12 seats respectively.
Leader of the cross-community Alliance Party, Naomi Long, voted along with her husband Michael at St Colmcille's parochial house in the east Belfast constituency where she was once MP.
All 90 seats were declared on Saturday morning with the DUP dropping from 38 to 28 and the Sinn Fein rising to 27.
Sinn Fein has lobbied against the DUP on such causes, and the new makeup of the chamber is expected to favour their cause, especially now a reduced DUP have lost their exclusive right to veto. But he again insisted that the party will not support DUP leader Arlene Foster as Northern Ireland's First Minister until she has been cleared of any wrongdoing related to the Renewable Heat Incentive (RHI) scandal, the failed energy scheme that is set to cost the public purse nearly £500 million.
Britain's Northern Ireland minister James Brokenshire emphasised the importance of a "frictionless" border during talks in Brussels this week, and promised to "take no risks" with political stability in the province.
Sinn Fein's party leader for Northern Ireland Michelle O'Neill talks to the media after toping the poll in Mid Ulster, Ballymena count centre, Northern Ireland, Friday, March 3, 2017.
The two blocs now have three weeks to establish a government run by both nationalists and unionists. "Sinn Fein can be absolutely assured that there will be no caving in to them".
Following Sinn Fein's success, the future of power-sharing in Northern Ireland remains unclear.
"If that means no deal and no new Stormont government, then so be it - we should return to direct rule".
Northern Ireland uses the single transferable vote (STV) proportional representation electoral system.
"She has my full support, she has the support of the party, and most importantly she has the support of 225,000 people across Northern Ireland who voted for the DUP, who increased the DUP's mandate", Hamilton told the BBC's Sunday Politics programme.
The election was called after the collapse of a coalition led by Arlene Foster's DUP and Sinn Féin's Martin McGuinness in January this year.
Mr McGuinness resigned over Mrs Foster's refusal to step aside as first minister pending an inquiry into the Renewable Heat Incentive (RHI) scheme, which could cost the Northern Ireland tax payer £490m.
The DUP will provide the first minister and Sinn Féin the deputy first minister (apart from the titles, the two are basically equal), although there may be a considerable amount of haggling involved first. Last year, DUP campaigned for the United Kingdom, including Northern Ireland, to leave the European Union. "Over 22,000 more voted DUP than in our record breaking election last May", she said.