Governor ESL Narasimhan administered oath of office and secrecy to Naidu and ministers at 7:27 pm at a public event at the Acharya Nagarjuna University near this town in south coastal Andhra.
Home minister Rajnath Singh and senior Bharatiya Janata Party (BJP) leader LK Advani attended the event, CNN-IBN reported.
The TDP has given two cabinet berths to its ally, the BJP. Naidu is the first chief minister of residual Andhra Pradesh after the separate Telangana state was carved out on June 2.
The 64-year-old had earlier served as the chief minister of undivided Andhra Pradesh from 1995 to 2004.
He was leader of opposition for nearly a decade.
The TDP bagged 102 seats in the 175-member Andhra Pradesh assembly in the recent elections. Its ally BJP won four seats.