Underlining that the country has touched "new heights" over the last 10 years, Priti Adani, Adani Foundation Chairperson, congratulated Prime Minister Narendra Modi as he took oath for a record third term.
Ms Adani, who attended the oath with her industrialist husband Gautam Adani, called the oath "historic".
"Congratulations to Prime Minister Shri @narendramodi ji on taking oath for his historic third term. Under your able leadership the country has touched new heights of progress in the last 10 years," Ms Adani posted on X in Hindi, with a picture of the PM taking oath.
Honour guards lined the steps of the Rashtrapati Bhavan where thousands gathered to watch PM Modi, dressed in a white kurta and with blue waistcoat, take the oath.
"We are confident that in the coming years your 'Developed India' campaign will move forward at double the speed," Ms Adani added.
South Asian leaders from neighbouring Bangladesh, the Maldives and Sri Lanka attended the ceremony but neighbouring rivals China and Pakistan had not sent top leaders.
But with PM Modi yet to announce his new cabinet, the line of lawmakers also taking the oath of office was keenly watched as an indication of who will be in government.
PM Modi was followed immediately by top BJP aides Rajnath Singh, Amit Shah and Nitin Gadkari.
Tenth to take the oath, and first among the BJP's coalition members, was HD Kumaraswamy from the Janata Dal (Secular) party.
Industrialist Mukesh Ambani, superstar Shah Rukh Khan, Rajinikanth, Akshay Kumar also attended the event.