Congress leader Mateen Ahmed, who was named pro-tem speaker, administered the oath to Kejriwal. Ahmed's name came up after Bharatiya Janata Party leader Jagdish Mukhi and Janata Dal-United's Shoaib Iqbal declined.
Urban Development Minister Manish Sisodia took oath after Kejriwal. Both of them, however, left the house soon after taking oath.
The other five ministers - Rakhi Birla, Girish Soni, Satendra Jain, Saurabh Bharadwaj and Somnath Bharti - also took oath. They were followed by other legislators.
The 28-member minority government of the AAP is to face the confidence vote Jan 2.
Congress legislators looked subdued while lawmakers from the Bharatiya Janata Party thumped the tables whenever their legislators stood up to take oath.
Arvinder Singh Lovely of the Congress was the lone legislator who took oath in English while Nand Kishore Garg and Naresh Gaur took oath in Sanskrit.
Anil Jha took oath in Maithili language.
Aam Aadmi Party supporters gathered outside the main gate of the Delhi Vidhan Sabha to watch their party leaders arrive for the first assembly session.
Kejriwal is leading a minority government. The AAP won only 28 seats in the 70-member assembly -- and will depend on the backing of the eight legislators of the Congress, which was voted out after 15 years of uninterrupted rule.
The BJP, which despite being the single largest party refused to form a government, will be the main opposition with 31 members.
After taking charge as chief minister, Kejriwal has fulfilled two major election promises made by the AAP. He cut power tariff by half to benefit an estimated 28 lakh households and announced that 667 litres of water would be provided free of charge to all households in the capital that have metered connections.
However, due to his sickness, Kejriwal has been staying home for the past few days after doctors advised him to take rest.
--IANS (Posted on 01-01-2014)