It was the culmination of a momentous campaign for people's rights that was mounted by Kejriwal and his Aam Aadmi Party (AAP) that was formed just a year ago and that rode to power in a major electoral upset this month.
Along with Kejirwal were sworn in six of his relatively youthful ministers by Delhi Lt Governor Najeeb Jung amid a crescendo of cheers and claps from his white cap-waving sea of supporters and voters who reposed faith in him and his promises to "change the system".
The 45-year-old Kejriwal's AAP won 28 seats in the 70-member Delhi assembly after the Bharatiya Janata Party failed to form a government despite winning 31 seats as it lacked majority in the house.
The AAP has the legislative backing of the eight-member Congress, which was routed after ruling Delhi for 15 long years.
Kejirwal and ministers wore common, everyday dress
All the seven people who took oath as ministers in Delhi's new government, including Chief Minister Arvind Kejriwal, wore their trademark white sidecaps emblazoned with the party''s name on one side and slogans on other in Hindi saying "I seek full freedom" and "I seek self-rule" and "I am a common man".
All were dressed simply in pullover and trousers. None wore formal suits or even jackets. Many wore colourful, everyday shirts in keeping with their 'common man' image. Kejirwal wore a checked shirt.
The only woman, Rakhi Birla, just 26, wore pink kameez and a black sleeveless jacket over a white salwar.
Earlier each of them had travelled like common commuters by Metro from their homes to the Ramlila Maidan, shunning the usual trappings of power like big cars and security cavalcade.
Promise never to give or take bribes: Kejriwal
Delhi's new Chief Minister on Saturday made people take a solemn pledge that they would never give or take bribes.
"We must promise we will never give or take bribes," said Kejriwal to the hundreds and thousands of his cheering supporters and citizens of Delhi at Ramlila Maidan after his swearing in.
"I promise I will never give bribes or take bribes," he said and asked people to repeat after him.
He said he would announce a telephone number in two days on which people could complain about any official demanding bribes.
"We shall catch the corrupt red-handed," said Kejriwal.