| Amata B.Grimm Power Limited | Asset Management Company of Power Station assets in Southeast Asia region | Infrastructure | Thailand |
| AVER ASIA (S) PTE. LTD. | Equipment rental in Singapore, Malaysia, Indonesia, Thailand, Myanmar, Cambodia | Transportation & Construction Systems | Singapore |
| Axiata Digital & Analytics Sdn Bhd | Digital marketing business | Media & Digital | Malaysia |
| Bangladesh SEZ Ltd. | Development, sales, and operation of industrial estate in Bangladesh | Infrastructure | Bangladesh |
| Calamba Steel Center Inc. | Steel service center (processing and sales) | Metal Products | Philippines |
| CS Metal Co., Ltd. | Steel service center (processing and sales) | Metal Products | Thailand |
| Dragon Logistics Co., Ltd. | Logistics Service | Infrastructure | Vietnam |
| Dunlop Tire (Thailand) Co., Ltd. | Import and wholesale of tires for Sumitomo Rubber Industries in Thailand | Transportation & Construction Systems | Thailand |
| First Philippine Industrial Park, Inc. | Development, Sales, and operation of industrial estate in Philippines | Infrastructure | Philippines |
| FujiMart Vietnam Retail LLC. | Supermarket in Vietnam | Living Related & Real Estate | Vietnam |
| HAL Vietnam Co., Ltd. | Manufacture and Sales of aluminum casting parts for automobiles | Transportation & Construction Systems | Vietnam |
| Hanoi Steel Center Co., Ltd. | Steel service center (processing and sales) | Metal Products | Vietnam |
| Health Connect Holdings Sdn. Bhd. | Provide Healthcare Management and Administration Service in Malaysia | Living Related & Real Estate | Malaysia |
| Insmart Joint Stock Company | Provide Healthcare Management and Administration Service in Vietnam | Living Related & Real Estate | Vietnam |
| Japan Sankofa Offshore Production Pte Ltd | FPSO Owning and Chartering Business for Oil and Gas Field, offshore Ghana | Mineral Resources, Energy, Chemical & Electronics | Singapore |
| Juice Products New Zealand Ltd. | manufacturing of squeezed juice from vegetables & fruit, mainly from carrots | Living Related & Real Estate | New Zealand |
| KDDI Summit Global Singapore Pte. Ltd. | Investment in KDDI Summit Global Myanmar Co., Ltd. | Media & Digital | Singapore |
| KIRIU (THAILAND) Co., Ltd. | Automotive components manufacturer (Disc rotor, Brake drum, etc.) | Transportation & Construction Systems | Thailand |
| Krisumi Corporation Private Limited | Condominium development in the northern Indian city of Gurugram in Haryana State | Living Related & Real Estate | India |
| Kuraray GC Advanced Materials Co., Ltd. | Manufacture Butadiene derivatives in Thailand | Mineral Resources, Energy, Chemical & Electronics | Thailand |
| Mactan Steel Center Inc. | Steel service center (processing and sales) | Metal Products | Philippines |
| Mahindra Industrial Park Chennai Limited | Development, sales, and operation of industrial estate in India | Infrastructure | India |
| Mekong Energy Company Ltd. | BOT(Build, Own, and Transfer) project for 20 years, Natural gas-fired combined cycle power plant of 715 MW at Phu My area in the Southern Vietnam | Infrastructure | Vietnam |
| Mukand Sumi Metal Processing Limited | Manufacturing and sale of secondary processed specialty steel and stainless steel products | Metal Products | India |
| Mukand Sumi Special Steel Limited | Manufacturing and sale of specialty rolled steel | Metal Products | India |
| MUNJAL KIRIU Industries Pvt. Ltd. | Automotive components manufacturer (Disc rotor, Brake drum, etc.) | Transportation & Construction Systems | India |
| Myanmar Japan Thilawa Development | Development, sales, and operation of industrial estate in Myanmar | Infrastructure | Myanmar |
| NORTH HANOI SMART CITY DEVELOPMENT INVESTMENT JOINT STOCK COMPANY | Smart City development in northern Hanoi City | Infrastructure | Vietnam |
| P.T. East Jakarta Industrial Park | Development, Sales, and operation of industrial estate in Indonesia | Infrastructure | Indonesia |
| P.T. Oto Multiartha | Financing of automobiles | Transportation & Construction Systems | Indonesia |
| P.T. Summitmas Property | Leasing of office buildings and warehouses | Living Related & Real Estate | Indonesia |
| P.T. Summit Oto Finance | Financing of motorcycles | Transportation & Construction Systems | Indonesia |
| PM Care Sdn. Bhd. | Provide Healthcare Management and Administration Service in Malaysia | Living Related & Real Estate | Malaysia |
| PT.Indomobil Summit Logistics | Logistics Service related to automobile | Infrastructure | Indonesia |
| PT. KIRIU INDONESIA | Automotive components manufacturer (Disc rotor, Brake drum, etc.) | Transportation & Construction Systems | Indonesia |
| PT. Premium Garansi Indonesia | Guarantee service for automobiles | Transportation & Construction Systems | Indonesia |
| PT. Super Steel Karawang | Steel service center (processing and sales) | Metal Products | Indonesia |
| PT. Traktor Nusantara | Dealer of Toyota Forklift and other equipment in Indonesia | Transportation & Construction Systems | Indonesia |
| PT. Weeo Solutions Frontier | Telematics & Smart Agriculture・IoT Service Provider in ASEAN country and India | Transportation & Construction Systems | Indonesia |
| PT Monotaro Indonesia | E-commerce business with a focus on subsidiary materials for factories in Indonesia | Media & Digital | Indonesia |
| PT Sumisho Global Logistics Indonesia | Warehousing & Distribution Services | Infrastructure | Indonesia |
| PT Supreme Energy Muara Laboh | Muara Laboh Geothermal Power Plant Project in Indonesia | Infrastructure | Indonesia |
| Saigon Steel Service & Processing Co., Ltd. | Steel service center (processing and sales) | Metal Products | Vietnam |
| Sakura Ferroalloys Sdn. Bhd | Production and marketing of manganese alloy | Mineral Resources, Energy, Chemical & Electronics | Malaysia |
| SC Metal Pty Ltd | Investment in aluminum smelting operation in Australia | Mineral Resources, Energy, Chemical & Electronics | Australia |
| SC Mineral Resources Pty. Ltd. | Investment in the Northparkes copper mine in Australia | Mineral Resources, Energy, Chemical & Electronics | Australia |
| SHOP Global (Thailand) Co., Ltd. | Developing a multimedia retail business with a focus on TV in Thailand | Media & Digital | Thailand |
| SMAS Auto Leasing India Private Limited | Leasing of motor vehicles | Transportation & Construction Systems | India |
| SSJ Consulting (Vietnam) LLC | Consultation services for port operation and logistics businesses in Vietnam | Infrastructure | Vietnam |
| Steel Centre (M) Sdn. Bhd. | Steel service centre (processing and sales), production and sales of steel products of construction | Metal Products | Malaysia |
| Sumiputeh Steel Centre Sdn. Bhd. | Steel service center (processing and sales) | Metal Products | Malaysia |
| Sumisho Global Logistics (Thailand) Co., Ltd. | Warehousing & Distribution Services | Infrastructure | Thailand |
| Sumisho Metal (Thailand) Co., Ltd. | Steel service center (processing and sales) | Metal Products | Thailand |
| Sumisho Motor Finance Corporation | Financing of motorcycles | Transportation & Construction Systems | Philippines |
| Sumitomo Mitsui Auto Leasing & Service (Thailand) Co., Ltd. | Leasing of motor vehicles | Transportation & Construction Systems | Thailand |
| Summit Auto Lease Australia Pty Limited | Leasing of motor vehicles | Transportation & Construction Systems | Australia |
| Summit Capital Leasing | Financing of motorcycles | Transportation & Construction Systems | Thailand |
| Summit Energy & Resources Pte. Ltd. | International trade of iron ore | Mineral Resources, Energy, Chemical & Electronics | Singapore |
| Summit Forests New Zealand Limited | Holding forest assets, Finance, Harvesting logs, Sales, Planting, Silviculture | Energy Innovation | New Zealand |
| Summit Rural (WA) Pty., Ltd. | Import, manufacture and sale of fertilizer in Western Australia | Mineral Resources, Energy, Chemical & Electronics | Australia |
| Summit SPA Motors Ltd. | Technology and advisory services for Hino brand truck, bus and provision of spare parts | Transportation & Construction Systems | Myanmar |
| Summit Sunrise Energy Co., Ltd | Holding Company of Small Power Producer Business etc. in Thailand | Infrastructure | Thailand |
| Thai Special Wire | Manufacture and sales of spring wires | Metal Products | Thailand |
| Thai Steel Pipe Industry Co., Ltd. | Manufacture and sales of welded steel tubes | Metal Products | Thailand |
| Thang Long Industrial Park (Vinh Phuc) Corporation | Development, sales, and operation of industrial estate in Vietnam | Infrastructure | Vietnam |
| Thang Long Industrial Park Corporation | Development, sales, and operation of industrial estate in Vietnam | Infrastructure | Vietnam |
| Thang Long Industrial Park II Corporation | Development, sales, and operation of industrial estate in Vietnam | Infrastructure | Vietnam |
| Thilawa Global Logistics Co.,Ltd | Logistics Service | Infrastructure | Myanmar |
| Tiki Corporation | Online retailer of books and other goods | Media & Digital | Vietnam |
| Toyota Summit Co., Ltd. | Retail and maintenance services for Toyota Motor Corporation in Thailand | Transportation & Construction Systems | Thailand |
| Union Harvest (M) Sdn.Bhd. | Import, manufacture and sale of fertilizer in Malaysia | Mineral Resources, Energy, Chemical & Electronics | Malaysia |
| Vietnam Nippon Steel Pipe Company Limited | Manufacture and sales of mechanical steel tubes mainly for motorcycles | Metal Products | Vietnam |
