ANKARA, Turkey — Recep Tayyip Erdogan was sworn in on Monday for a five-year term under a new Constitution that gives Turkey’s president sweeping executive powers. He promptly named his son-in-law finance minister, an appointment that unsettled financial markets and raised new concerns about the concentration of so much power in one politician.

“We as Turkey, and the Turkish nation, are making a new start here in your presence,” Mr. Erdogan told hundreds of foreign leaders, dignitaries and party members gathered in the gardens of the presidential palace in Ankara, the capital. “We will make major moves in every area from macroeconomic balances to investments to make Turkey one of the 10 biggest economies of the world.”

Mr. Erdogan, who has been at the helm of Turkish politics since 2003, received a fresh mandate from voters last month on promises to make Turkey more efficient, and a great and strong state. As a result of a referendum he championed last year, the once-ceremonial presidency has vastly expanded powers.

Whether Mr. Erdogan can get a grip on the shaky Turkish economy is another matter. Government debt has exploded, fueled by borrowing for vast infrastructure projects, many of them built by contractors with ties to Mr. Erdogan and his allies. Turkey’s economy is still one of the world’s fastest growing, expanding at a rate of 7.4 percent last year, but the lira has fallen recently, a reflection of creditors’ and investors’ anxieties.