| Year | Detail |
| 2005 |
Mitsubishi Chemical Corp. and Mitsubishi Pharma Corp jointly established Mitsubishi Chemical Holdings Corp. |
| 2007 |
Mitsubishi Plastics Inc. became a wholly-owned subsidiary of Mitsubishi Chemical Holdings Corp. |
| 2007 |
Mitsubishi Pharma Corp. and Tanabe Seiyaku Co. Ltd. merged and became a listed subsidiary of Mitsubishi Chemical Holdings Corp. as Mitsubishi Tanabe Pharma Corp. |
| 2008 |
Mitsubishi Chemical Corp., Mitsubishi Plastics Inc., Mitsubishi Polyester Film Corp, Mitsubishi Chemical Functional Products Inc., and Mitsubishi Chemical MKV Co. were amalgamated to become a consolidated new company, Mitsubishi Plastics Inc. |
| 2010 |
Mitsubishi Rayon Co. Ltd. became a consolidated subsidiary of Mitsubishi Chemical Holdings Corp. |
| 2010 |
Mitsubishi Chemical Holdings America Inc. was established. |
| 2011 |
Mitsubishi Chemical Holdings (Beijing) Co. Ltd. was established. |
| 2013 |
Qualicaps Co. Ltd. became a subsidiary of Mitsubishi Chemical Holdings Corporation. |
| 2013 |
Mitsubishi Chemical Holdings Corp Staff Inc. was established. |
| 2014 |
Taiyo Nippon Sanso Corp. became a subsidiary of Mitsubishi Chemical Holdings Corp. |
| 2018 |
Diamond Edge Ventures Inc. was established. |
| 2020 |
Mitsubishi Tanabe Pharma Corp. became a subsidiary of Mitsubishi Chemical Holdings Corp. |
| 2022 |
Mitsubishi Chemical Holdings Corp. changed its tradename to Mitsubishi Chemical Group Corp. |