A count of nearly over 95 percent for the parliamentary election also showed that Erdogan's AKP - along with its Nationalist Movement Party (MHP) allies - were well ahead and set for an overall majority.
Several world leaders supportive of Erdogan, including Azerbaijani President Ilham Aliyev and Qatari Emir Tamim bin Hamad al-Thani, called to congratulate him on his "victory", the presidency said.
Yet, with unofficial results from the state-run Anatolian News Agency (AA) declaring that he had won 52.65% of the vote, it seems Turks narrowly chose to back the man who has effectively led Turkey since 2002, first as prime minister and then as president.
Some 50,000 people have been arrested and 110,000 civil servants have been fired under the emergency, which opposition lawmakers say Erdogan has used to stifle dissent.
Ahead of the election, he took steps to abolish the position of prime minister and transfer all of the position's executive power to himself.
"I remember when we had to wait five days to get bread", said 56-year-old Tuncay Tek, who said he voted for Erdogan and the AKP on Sunday. Erdogan's closest competitor, Ince, vowed that he would lift the state of emergency within 48 hours if elected president and reverse all the constitutional reforms afterward.
Addressing thousands of supporters in Ankara, he said: "We will fight even more with the strength you provided us with this election".
Two votes are being held on Sunday - one to choose Turkey's next president, and another to pick members of parliament.
Critics say it would allow Erdogan to effectively rule by fiat, while curbing independent checks on his power.More news: Brazil vs Costa Rica : How Coutinho, Neymar broke dogged Costa Rica
Erdogan, 64, the most popular but also the most divisive politician in modern Turkey, added that Turkish forces would continue to "liberate Syrian lands" so that the 3.5 million Syrian refugees in Turkey could return home safely.
The main opposition Republican People's Party (CHP) will have 146 seats, the pro-Kurdish HDP 67 and the breakaway nationalist Iyi Party 44.
His supporters say only Erdogan can guarantee Turkey's economic and political stability in hard times.
The lira TRYTOM=D3 currency, which has lost some 20 percent of its value this year, rallied some 2 percent in early trade, while stocks .XU100 rose more than 1 percent, after an early surge, as investors bet that the result would lead to political stability - a positive for financial markets.
If 7 to 8 per cent of formerly loyal voters abandon the president's Justice and Development Party, or AKP, the governing party will lose, said Ozer Sencar, who runs the independent Metropoll polling agency.
Turkey's global TV network announced Mr Erdogan was the victor when just 91 percent of votes had been counted.
More than 59 million Turkish citizens, including some 3 million living overseas, are eligible to vote on Sunday.
Additionally, as NPR's Peter Kenyon reported, the new system grants Erdogan the possibility of running for a third term "should parliament call snap elections in his final term".