Utilitywarehouse Members include energy services companies, manufacturers, distributors, engineering and construction firms, and services providers. The following companies are now or have been Members of the Utilitywarehouse:
| Airvac Tech Services | General Electric | Priester Supply |
| Alabama Power Co./Southern Co. | General Pacific, Inc. | Public Service Company of Oklahoma |
| Arizona Electric Power Cooperative | Georgia Power Co./Southern Co. | Puget Sound Energy, Inc. |
| Arizona Public Service Co. | Global Power Resource | Raylew Power Systems, Inc. |
| ATEL Capitol Group | Grafton Utility Supply Ltd. | Reed City Power Line Supply |
| AVISTA | Heuett Construction | Reel Solutions |
| Baltimore Gas and Electric Company | Hunt & Gather | Reels & Spools |
| Basin Electric Power Cooperative | Industrial Electric Motor Service Inc. | Reliant Energy |
| Bay Ltd. | Jacksonville Electric Authority | Roblicorp |
| Bayne Co., The | Jerry Dill Associates, Inc. | ROMAC |
| BC Hydro | Liberty Machine Repair | S & S Turbine |
| BCS Switchgear | Lincoln Electric System | Safety Consulting Services |
| Belyea Company, Inc. | Maine Yankee | Salt River Project |
| Bonneville Power Administration | Manfredi's Cold Storage & Distribution | San Joaquin Valley Energy Partners, L.L.P. |
| Border States Electric | Marcor Remediation, Inc. | Sapphire Group |
| Brenco, Inc. | Markerry Electrical Equipment | SASCO Inc. |
| Brinkley Manufacturing | Martin & Martin Auctioneers, Inc. | Scuba Air Compressor Service, Inc. |
| British Columbia Hydro and Power Authority | MDM Sales | Sermatech Gas-Path |
| Brownstown Electric Supply Co. | Mercer Process Equipment | Service Marketing |
| C.I.E. | Miami Transformers | Snohomish County Public Utility District No. 1 |
| Central Maine Power Company | Millennium Metals, Inc. | Solomon Corporation |
| Cinergy | Morgan Stanley | Southern California Edison |
| Circuit Breaker Sales Company, Inc. | Mortgage Investors Corp. | Southern Company |
| City of Burlington | NAUD, National Association of Utility Distributors | Southwest Power Systems, Inc. |
| Clallam County Public Utility District No. 1 | Nebraska Public Power District | Springfield City Water, Light & Power |
| Connector Express | Nevada Power Company | Springfield, IL Water, Light & Power |
| Consolidated Edison Company of New York, Inc. | New England Power Company | St. Jean and Associates |
| Consolidated Surplus | New York Power Authority | Sunbelt Transformer |
| Consumers Energy | Nexans Energy USA | Surelco |
| Consumers Power Company | Niagara Mohawk Power Corporation | T&R Electric |
| Cooper Power Systems | Northern Breakers & Electrical Supply | Tacoma Public Utilities |
| Delmarva Power and Light Co. | Northwest Pulp and Paper Equipment Company | Tampa Electric Co. |
| Delta Technologies, Inc. | Northwestern Public Service Company | Taylor Equipment |
| Denver International Steel & Pipe Supply | Nova Scotia Power, Inc. | Techline Inc. Austin |
| Dispatch Welding & Erectors, Inc. | Nu-Dell Manufacturing | Tech-Parts Inc., Richard Jenkins |
| DoveBid.com formerly Trade-out.com | Oglethorpe Power Corp. | Texas Electric Cooperatives |
| Duquesne Light Company | Oklahoma Gas and Electric Company | The Sapphire group L.L.C. |
| Edwards Manufacturing Co. | Ontario Power Generation | TransAlta Utilities Corp. |
| Electric Service Company | P & S Transformer Corporation | Transformer Network, Inc. |
| Energy Consulting Group | Pacific Gas and Electric Co. | |
| Enron | Pacificorp | Tucson Transformer & Apparatus |
| Entergy Corporation | Park Corporation | Universal Equipment Company |
| Farrell Electric | Plant Research Corporation | Virginia Electric and Power Company |
| Farris, Vaughn, Wills & Murry, Barristers & Solicitors | Porcelain Products Company | Walters Power International |
| First Capitol Group | Portland General Electric Company | Westcoast Power Inc. |
| Florida Power and Light Co. | Power & Telephone Supply | West Coast Engineering Group Ltd. |
| G&S Technologies | Power Engineers | Wisconsin Electric Power Company |
| Power Equipment Specialists, Inc | Wisconsin Public Service Corporation | |
| Power Gem Engineers | York County Rural Public Power District | |
| Power Generation Systems Intl, Inc. |