The ceremony was held at Rashtrapati Bhavan, the official residence of the President of India.
The National Democratic Alliance, led by Prime Minister Narendra Modi's Bharatiya Janata Party, won the election with 293 seats, a smaller margin than exit polls had predicted.
In this election, the Indian opposition appeared again and won 234 seats.
Thousands of guests attended his swearing-in at Rashtrapati Bhavan in Delhi. These are the leaders of Bangladesh, Nepal, Sri Lanka and the Maldives.
Security was tightened in Delhi, which was declared a no-fly zone, and more than 2,500 policemen were deployed around the scene.
During the meeting, President Draupadi Murmu also promised a ministerial meeting of Prime Minister Modi's new cabinet.
Opinion polls show a victory for the Bharatiya Janata Party, which has ruled India for a decade but lost its parliamentary majority in the election.
His NDA party is expecting its two allies - the Telugu Democratic Party (TDP) and the Janata Party (United) JD(U) - to get the 272 seats needed to form the government. Voters on Friday elected Prime Minister Narendra Modi as the leader of the Lok Sabha (lower house of parliament), the leader of the Bharatiya Janata Party (BJP) and the leader of the National Democratic Alliance ( NDA).
It is not clear what concessions his partners may negotiate in exchange for their support. Indian media reported that some of them were seeking prime ministerial posts.
India's opposition, led by the Congress party, said the election was a coup for Prime Minister Narendra Modi's government.
However, Prime Minister Narendra Modi on Friday refuted the claims, saying: "The opposition is trying to project the results of the 2024 Lok Sabha elections as defeat. But we never lost, never lost, never again.
Prime Minister Modi thanked voters for the mandate and said "he will do his best" to eradicate corruption and poverty.
"Empowering the poor and the middle class is our priority," he said.
During the campaign, Prime Minister Modi and his party were accused by critics of using hate speech, attacking the country's Muslim minority, and imprisoning the opposition.
On Friday, the Prime Minister-elect said the NDA alliance was "adhered to the principle of 'sarva panth sambhava' (religious equality).
The Union of India says it will fulfill its responsibilities in Parliament by running the government and protecting the constitution.