Ono Kotomi was born on October 7, 2002 in Tokyo, Japan.
Ono was enrolled in Avex Artist Academy's dance program in Tokyo.
Ono modeled in the June 22 issue of fashion magazine JS Girl.
During the summer, Ono participated in the 2015 ANGERME Shin Member Audition, but did not pass.
On January 15, Ono joined Hello Pro Kenshuusei alongside Noguchi Kurumi, Kodama Sakiko, Yonemura Kirara and Kiyono Momohime. She was introduced at Hello! Project Kenshuusei Happyoukai 2016 2gatsu・3gatsu ~SINGING!~ on February 13.
On October 2, she participated in a fanclub event titled Hello Pro Kenshuusei Special Event in Nagoya ~Hajimemashite! 5~ at Midland Square Cinema 2 alongside Yamada Ichigo, Shutto Anna and Kanemitsu Ruru.
Ono participated in the opening act and challenge act for the Morning Musume '19 Concert Tour Haru ~BEST WISHES!~.
On July 26, the list of members appearing in Hello! Project Kenshuusei Happyoukai 2019 9gatsu ~Kira~ was released, and it was announced that Ono had completed her training.
On June 1, she opened up a Twitter and an Instagram account.
- Name: Ono Kotomi (小野琴己)
- Nickname: Onokoto (おのこと)
- Birthdate: October 7, 2002
- Birthplace: Tokyo, Japan
- Blood Type: B
- Height: 165 cm (5 ft 4.9 in)?
- Western Zodiac: Libra
- Eastern Zodiac: Horse
- Hello! Project Status:
- 2016-01-15: Hello Pro Kenshuusei member
- 2019-07-26: Left
- UP-FRONT PROMOTION Status:
- 2016-01-15: Member
- 2019-07-26: Left
- Hello! Project Groups:
- Hello Pro Kenshuusei (2016-2019)
- Other Groups:
- Avex Academy Trainee (2015-2016)
-  JK Ninja Girls (cameo)
- [2016-2019] Hello! Project Station
- She considers herself an airhead.
- She has been taking guitar lessons since 6th grade.
- Her future goal is to become a member of a group, wear cute clothes and appear on stage and on TV.
- She shares her birthday with Morning Musume member Nonaka Miki.
- She has the same last name as Tsubaki Factory member Ono Mizuho.
- Gallery:Ono Kotomi
- List:Ono Kotomi Discography Featured In
- List:Ono Kotomi Concert & Event Appearances
- "ハロプロ研修生に新メンバーが加入！" (in Japanese). Hello! Project. 2016-01-15.
- "「Hello! Project 研修生発表会 2019 9月」タイトル・出演者・チケット発売日決定！" (in Japanese). Hello! Project. 2019-07-26. (Archived)
- Used by Dambara Ruru, Maeda Kokoro, Kanatsu Mizuki, Kodama Sakiko and Nishida Shiori.
- Ono's Instagram Bio
- BOMB September 2018 Issue.