| C-Hear | Texas |
| C-leveled | Pennsylvania |
| C-Net Systems, Inc. | Michigan |
| C-Ram, Inc. | North Dakota |
| C-Scape Consulting Corporation | New York |
| C-Sharp Technologies, Inc. | Ohio |
| C-spec | California |
| C-Squared Internet Solutions | Texas |
| C-Systems Software, Inc. | Texas |
| C. Crane Company, Inc. | California |
| C.A. Web Design, Inc. | California |
| C.E. Communication Services, Inc. | Massachusetts |
| C.E. Electronics, Inc. | Ohio |
| C.E.M. Systems | Kansas |
| C.H. Local Media, LLC | |
| C.H. Robinson Worldwide, Inc. | Minnesota |
| C.Light Technologies, Inc. | Massachusetts |
| C.Link, LLC | Idaho |
| C.W. Detrixhe | Oklahoma |
| C/C/G | California |
| C/F Data Systems, LLC | Massachusetts |
| C0MPLÉX1 | |
| C100 Association | California |
| C2 Digital | |
| C2 Solutions | |
| C2 Strategic Communications | |
| C2 Systems, LLC | Texas |
| C2 Technologies, Inc. | Virginia |
| C2FO | Kansas |
| C2G | Ohio |
| C2G Media Group, LLC | Michigan |
| C2Home & Office, Inc. | New Jersey |
| C2i Genomics | New York |
| C2i Technologies | |
| C2M Management | |
| C2N Diagnostics | Missouri |
| C2Perform | Georgia |
| C3 Computer Services | Nevada |
| C3 Group Marketing | |
| C3 IoT | California |
| C3 Tech | Indiana |
| C360 Software, Inc. | Texas |
| C3i3 Interactive, Inc. | California |
| C4 Imaging | |
| C4 Tech & Design | Louisiana |
| C4 Therapeutics, Inc. | |
| C42D Creative, Inc. | |
| C4i Technologies, Inc. | |
| C5 Insight | North Carolina |
| C6 Launch Systems, Inc. | |