| Year | Detail |
| 1919 |
The House of Sumitomo establishes an independently managed fertilizer plant in Niihama, Ehime prefecture. |
| 1915 |
Operations commence for calcium superphosphate fertilizer. |
| 1925 |
Sumitomo Fertilizer Manufacturing Co. Ltd. is incorporated. |
| 1934 |
Sumitomo Fertilizer Manufacturing changes its name to Sumitomo Chemical Co. Ltd. |
| 1944 |
Sumitomo acquires Japan Dyestuff Manufacturing Company. |
| 1949 |
It takes over the aluminum business of Sumitomo Aluminium Smelting Co. Ltd. |
| 1958 |
Sumitomo starts the production of ethylene and its derivatives. |
| 1965 |
The Takatsuki Research Laboratory is established. |
| 1978 |
Misawa Works is opened to expand the production of household insecticides involving pyrethroids. |
| 1982 |
P.T. Indonesia Asahan Aluminium starts operations. |
| 1984 |
The petrochemical complex in Singapore begins operations. |
| 1989 |
The Tsukuba Research Laboratory is established. |
| 2001 |
Sumitomo acquires the household insecticide business of Aventis Crop Science. |
| 2005 |
It forms a joint venture, Rabigh Refining and Petrochemical Company (Petro Rabigh), with Saudi Aramco. |
| 2007 |
Sumitomo acquires the UK company Cambridge Display Technology. |
| 2017 |
It opens a plant for the production of separators for lithium-ion secondary batteries at SSLM, a subsidiary in South Korea. |
| 2019 |
Sumitomo Dainippon Pharma (now Sumitomo Pharma) enters into a strategic alliance with Roivant Sciences Ltd. |
| 2020 |
Sumitomo acquires four South American subsidiaries of a leading Australian agricultural chemical company, Nufarm Ltd. |