2000 was the year in which Ishiguro Aya and Ichii Sayaka graduated Morning Musume and Hello! Project; the 4th generation joined Morning Musume; Maeda Yuki and Matsuura Aya joined Hello! Project; Miyoshi Chinatsu left Hello! Project; Sheki-Dol and Minimoni were formed; T&C Bomber disbanded; Chelsea and April left Coconuts Musume; and Lehua joined Coconuts Musume.
Members
- January 7: Ishiguro Aya graduates Morning Musume and Hello! Project
- January ?: Chelsea and April leave Coconuts Musume and Hello! Project
- February 10: Nomura Minami is born
- February 19: Morito Chisaki is born
- March 27: Ogawa Rena is born
- March ?: Taiyou to Ciscomoon becomes T&C Bomber
- April 1: Kishimoto Yumeno is born
- April 12: Maeda Yuki joins Hello! Project
- April 16: Ishikawa Rika, Yoshizawa Hitomi, Tsuji Nozomi, and Kago Ai join Morning Musume as the 4th generation
- April 26: Hamaura Ayano is born
- April ?:
- Lehua joins Coconuts Musume and Hello! Project
- May 21: Ichii Sayaka graduates Morning Musume and Hello! Project
- June 4: Ishikawa Rika and Kago Ai join Tanpopo
- June 26: Yoshizawa Hitomi joins Petitmoni
- July 11: Sheki-Dol is formed
- July 21: Taguchi Natsumi is born
- August 29: Matsuura Aya joins Hello! Project
- August 31: Inoue Hikaru is born
- September 10: Oura Hirona is born
- September ?: Miyoshi Chinatsu leaves Hello! Project
- October 9: T&C Bomber disbands
- October 22: Minimoni is formed
- December 27: Wu Zhao Xian is born
Singles
- January 26: Koi no Dance Site - Morning Musume
- February 19: Amai Anata no Aji - Melon Kinenbi (debut)
- March 8:
- April 2: Naki Usagi - Maeda Yuki (debut)
- April 19: DON'T STOP Ren'aichuu - T&C Bomber
- April 27: Hokkaido Shalala - Country Musume
- May 17:
- Happy Summer Wedding - Morning Musume
- One Room Natsu no Koi Monogatari - Heike Michiyo
- Tokonatsu Musume - Coconuts Musume
- May 31: Anata no Shirts to Love song - Miyoshi Chinatsu
- June 28: Kokuhaku Kinenbi - Melon Kinenbi
- July 5: Otome Pasta ni Kandou - Tanpopo
- July 12: Shanghai no Kaze - Nakazawa Yuko
- July 19: HEY! Mahiru no Shinkirou - T&C Bomber
- July 26:
- Watashi mo "I LOVE YOU" - Coconuts Musume
- Seishun Jidai 1.2.3! / Bicycle Daiseikou! - Petitmoni
- July 31: Koi ga Suteki na Kisetsu - Country Musume
- August 9: Ai no Chikara - Heike Michiyo
- September 6: I WISH - Morning Musume
- October 25: Super Jet Shoes ~Mirai wo Aruku Kutsu~ - Peachy (debut)
- November 1: Kokoro no Pheromone - Sheki-Dol (debut)
- December 6: Snow Paradise - Ishii Rika
- December 13: Ren'ai Revolution 21 - Morning Musume
Albums
- March 29: 3rd -LOVE Paradise- - Morning Musume
- April 26: Petit Best ~Ki Ao Aka~ - Hello! Project
- September 13: For ourself ~Single History~ - Heike Michiyo
- September 27: 2nd STAGE - T&C Bomber