Bhagwant Mann was administered the oath by Punjab Governor Banwarilal Purohit.
Bhagwant Mann became Punjab Chief Minister today after a grand yellow-themed oath ceremony at Khatkar Kalan, freedom fighter Bhagat Singh's village. Delhi Chief Minister Arvind Kejriwal and other senior Aam Aadmi Party (AAP) leaders, wearing "Basanti (yellow)" turbans, were on stage during the ceremony.
Bhagwant Mann said a golden chapter has started in the history of the state and that it would be "badhta (progressive) Punjab, rather than Udta Punjab", referencing the 2016 blockbuster that highlighted Punjab's drug problem.
"I'm not here to diss anyone today. I am the Chief Minister of everyone in Punjab, even those who did not vote for our party," he said.
Yellow turbans and scarves were scattered across the venue, and the village, for the ceremony. Mr Mann had announced the dress code in his video appeal.
Addressing newly elected MLAs of his party, Mr Mann said: "I appeal to you all to not get arrogant. We have to respect even those who didn't vote for us."
Mr Mann, who is known by the trademark "Basanti (yellow)" turban inspired by Bhagat Singh, also quoted the legendary freedom fighter.
"Ishq karna sabka paidaishi haq hai kyun na is baar watan ki sarzamin ko mehboob bana liya jaye (love is our birth right. Why not make our motherland our love this time?)," Mr Mann recited.
AAP registered a magnificent victory in the recent Punjab election, winning 92 seats in the 117-seat assembly and beating incumbent Congress by a vast margin. This is the eight-year-old party's second state after Delhi.
Soon after the results, Mr Mann declared that he would take oath, not in the Governor's House, as is tradition, but at Bhagat Singh's village.
"Earlier, oath ceremonies used to take place in palaces. I have a special place for Bhagat Singh in my heart," he told the gathering.
Besides the spot where the ceremony took place, a large area was cleared of wheat crops for use as parking space, say reports.
Mr Mann, 48, is the youngest Chief Minister of the state since the 1970s. He resigned as Lok Sabha MP yesterday.