The Governor administered the oath of office and secrecy to Gogoi in Assamese at the Durbar Hall of the Raj Bhawan.
Union DoNER Minister, Bijoy Krishna Handique, Meghalaya Chief Minister, Mukul Sangma and Assam Pradesh Congress President, Bhubaneswar Kalita, were among those who attended the swearing-in ceremony.
76-year-old Gogoi, wearing white kurta and pyjama and a waistcoat, came with wife Dolly, son Gaurav and daughter Chandrima at the function.
He is scheduled to visit Delhi to get his list of ministers finalised by Congress President, Sonia Gandhi.
77 newly-elected Congress MLAs, 12 MLAs of ally Bodoland Peoples' Front's led by Hagrama Mohilary, senior civil, police and army officials attended the event.