Greek conservative Mitsotakis sworn in as prime minister
Mitsotakis took the oath in a ceremony conducted by the Archbishop of Greece Ieronymos as his wife and three children watched.
New Democracy won nearly 40 percent of the vote, unseating Alexis Tsipras' Syriza party, which got 31.53 percent.
The win appeared driven by fatigue with years of European Union-enforced belt-tightening, combined with high unemployment, after the country almost crashed out of the euro zone at the height of its financial travails in 2015.
Tsipras took over from the conservatives in 2015 as Greece was at the peak of a financial crisis which had ravaged the country since 2010.
Initially vowing to resist deeper austerity, he was forced into signing up to another bailout months after his election, a decision which went down badly with voters.
Mitsotakis will likely face an uphill battle squaring his promises with fiscal targets agreed with lenders.