| Name | Employees | Description of Operations |
| Port Colborne Poultry (Pinty's Delicious Foods) | 229 | Processed chicken-whole or cut up, boneless white and dark meat and chicken fingers |
| Vale Canada Limited | 200 | Cobalt refinery, precious metals refinery and nickel processing facility |
| J. Oskam Steel Fabricators Ltd. | 150 | Storage bins, dust collectors, stainless steel tanks, pipes and plant maintenance, crane service and custom machining |
| PC Forge | 108 | Steel forging |
| ADM Milling | 95 | Flour and bakery mixes for commercial bakeries, soft and hard flour |
| Thurston Machine Co. Ltd. | 85 | Fabricator, machining and assembly and testing of build to print steel mill equipment including mandrels and tension reels |
| JTL Machine Ltd. | 78 | Heavy custom machining and fabricating of steel mill, mining and paper mill equipment |
| Jungbunzlauer Canada Inc. | 74 | Manufacturer of citric acid and trisodium citrate |
| Brennan Paving Ltd. | 70 | Road and bridge construction, milling, asphalt paving and heavy civil |
| Allied Marine & Industrial | 50 | Performance precision machining, repair and overhaul of machinery and fabrication of material handling system components; Heavy industrial and ship repair |
| Algoma Central Corp | 50 | Ship repair |
| Wainfleet Box & Pallet Limited | 45 | Pallets, boxes, plastics and corrugated. Export lumber certified pallets for EU hardwood or softwood |
| International Marine Salvage Inc. | 35 | Hazardous and non-hazardous waste transporters, scrap metal processors and transporters; shipbreakers and marine artifacts |
| Barber Hymac Hydro Inc. | 33 | Hydraulic turbines, general machining, plant maintenance, custom designing, components and installation |
| Data sourced from 2012 Port Colborne Employer Survey of Largest Employers | ||