Russian Prime Minister Dmitry Medvedev was present, in a new sign of the warm ties between Ankara and Moscow, as was Venezuelan President Nicolas Maduro, regarded with disdain by Washington but an ally of Erdogan.
"As president, I swear upon my honor and integrity, before the great Turkish nation and history, to work with all my power to protect and exalt the glory and honor of the Republic of Turkey", Erdogan said in his speech to Parliament after being sworn in.
"Everything went well in the eyes of the people".
As Turkey's first executive president, Erdogan now can rule by decrees, outline the state budget and announce a state of emergency.
Recep Tayyip Erdogan has taken the presidential oath of office to become the Republic of Turkey's first president under its new governmental system.
And unlike the North Atlantic Treaty Organisation summit in May 2017 - where the president famously shoved Montenegro's Prime Minister Dusko Markovic out of the way so he could be in the front row of the group photo - other leaders gave him plenty of space and he stood alone, front and center.
Earlier, the government issued a decree adjusting Turkey's laws to the new presidential system that comes into effect with the elections.
Investors have previously been anxious about the independence of the Central Bank of the Republic of Turkey, after President Recep Tayyip Erdogan said he wanted to take more responsibility in his country's monetary policy. Previously, the prime minister formed the government by making elected members of parliament ministers.
Erdogan will this week immediately turn to foreign policy, visiting northern Cyprus and Azerbaijan, followed by more challenging encounters at a North Atlantic Treaty Organisation summit in Brussels where he will meet US President Donald Trump and other leaders.
In a bid to create a more streamlined government, there are expected to be 16 ministries, down from the current 26. Critics say the new system undermines impartiality.
Erdogan's son-in-law Berat Albayrak, a former energy minister, has been appointed minister of treasury and finance, overseeing the economy.
"There is no stopping for us until we bring Turkey - which we saved from plotters, coupists and political and economic hitmen, street gangs and terrorist organisations - to among the top 10 economies in the world", he said.
Inflation surged last month above 15 percent, its highest level in more than a decade, despite interest rate hikes of 500 basis points by the central bank since April.
The People's Alliance formed by the ruling Justice and Development Party and the Nationalist Movement Party has secured most seats in national parliament with 53.6% of the vote. A special one lira coin (less than 25 USA cents) was minted for guests with the image of the presidential palace, dated July 9, 2018. Erdoĝan has repeatedly clashed with strategic allies such as the U.S. and the European Union in recent years over the war in Syria, Turkey's accession to the EU, human rights abuses by Ankara, Europe's failure to support Turkey during the coup attempt, and rising Islamophobia in Europe.