Senior AAP leader Atishi was administered oath as the eighth Chief Minister of Delhi by Lieutenant Governor V K Saxena on Saturday.
Saxena administered the oath of office and secrecy to Atishi. She was chosen as the leader of the legislature party earlier this week, after her predecessor Arvind Kejriwal decided to resign.
Senior AAP leaders Kejriwal and Manish Sisodia were also present at the swearing-in event.
Atishi is Delhi's third woman chief minister after Congress' Sheila Dikshit and BJP's Sushma Swaraj.
She also becomes the 17th woman to hold the post of chief minister in independent India.
Atishi, however, will have a brief tenure in office as assembly elections in the national capital are due in February.
