January 21, 2016: The first episode of reality show Produce 101 airs. All the girls are participating in the show to hopefully becoming members of a girl group.

April 1, 2016: Reality show Produce 101 finishes airing. The members of I.O.I. are announced. The girls prepare for their training and promotions.

April 5, 2016: The group has a "pre-debut" with their single from the show, "Crush" and accompanying MV
The girls start their own reality show called Standby I.O.I.

May 4, 2016: The group has their official debut with mini album "Chrysalis" and title track "Dream Girls" and MV

May 11, 2016: Chaeyeon goes on hiatus to complete promotions with her girl group DIA

June 7, 2016: Mina and Sejeong go on hiatus to prepare for their debut in girl group Gugudan

June 10, 2016: Yeonjung is pulled out of I.O.I. by her company to complete more training

July 2016: The remaining members host a show, called LAN Cable Friends I.O.I.

August 9, 2016: As an un-official sub-unit, I.O.I. members Somi, Yoojung, Chungha, Sohye, Kyulkyung, Doyeon, and Nayoung release single "Whatta Man (Good Man)" and MV

August 15, 2016: I.O.I.'s sub-unit releases "Hand in Hand" cover

August 31, 2016: I.O.I. releases "I Love You, Remember" for Moon Lovers OST

October 16, 2016: I.O.I. hosts a comeback show titled I Miss You Very Very Very Much

October 17, 2016: The full group (all 11 members) releases "Miss Me?" mini album with title track "Very Very Very" and MV

January 18, 2017: I.O.I. releases their final single, "Downpour" and MV

January 20-22, 2017: I.O.I. holds their only concert, "Time Slip - I.O.I."

January 31, 2017: I.O.I. officially disbands. The members have said they would like to reunite in five years.