| MARTIN COUNTY LEAGUE OF CONSUMERS, INC. | — | N02185 | 1984-03-26 | Inactive | STUART |
| MARTIN COUNTY LEGAL CLINIC, INC. | — | 609246 | 1979-02-08 | Inactive | STUART |
| MARTIN COUNTY LITERACY COUNCIL, INCORPORATED | — | 766818 | 1983-02-03 | Inactive | STUART |
| MARTIN COUNTY LOCK AND SECURITY, INC. | — | 542003 | 1977-08-02 | Inactive | STUART |
| MARTIN COUNTY LOCKSMITH LLC | — | P25000059119 | 2025-10-24 | Active | STUART |
| MARTIN COUNTY MAINTENANCE SERVICES, INC. | — | 684893 | 1980-08-20 | Inactive | STUART |
| MARTIN COUNTY MANAGEMENT CORP. | — | 420484 | 1973-03-06 | Inactive | STUART |
| MARTIN COUNTY MANAGEMENT CORP. | — | H13881 | 1984-07-25 | Inactive | STUART |
| MARTIN COUNTY MARINE CONSTRUCTION, INC. | — | P04000147354 | 2004-10-25 | Inactive | STUART |
| MARTIN COUNTY MARINERS, CORP | — | N22000006136 | 2022-06-02 | Active | STUART |
| MARTIN COUNTY MARTIAL ARTS LLC | — | L16000092920 | 2016-05-17 | Inactive | STUART |
| MARTIN COUNTY MASONRY CONTRACTORS, INC. | — | 505133 | 1976-06-08 | Inactive | STUART |
| MARTIN COUNTY MEDICAL MANAGEMENT, INC. | — | 603581 | 1972-06-27 | Inactive | STUART |
| MARTIN COUNTY MEDICAL SOCIETY ALLIANCE, INC. | — | N95000005574 | 1995-11-27 | Inactive | STUART |
| MARTIN COUNTY MEDICAL SOCIETY AUXILIARY, INC. | — | N19411 | 1987-02-25 | Inactive | STUART |
| MARTIN COUNTY MILLWORK, INC. | — | K72656 | 1989-03-09 | Inactive | STUART |
| MARTIN COUNTY MINING AND RECYCLING, INC. | — | P11000043770 | 2011-05-05 | Inactive | STUART |
| MARTIN COUNTY MODEL RAILROADERS, INC. | — | N09000011671 | 2009-12-07 | Active | STUART |
| MARTIN COUNTY MONTESSORI, INC. | — | V21667 | 1992-03-16 | Inactive | STUART |
| MARTIN COUNTY MORTGAGE BROKERS, INC. | — | P98000016277 | 1998-02-18 | Inactive | STUART |
| MARTIN COUNTY MOTORS, INC. | — | G94218 | 1984-04-02 | Inactive | STUART |
| MARTIN COUNTY OFFICE PLAZA, L.L.C. | — | L03000031606 | 2003-08-20 | Inactive | STUART |
| MARTIN COUNTY OHV CLUB, INC. | — | N08000002822 | 2008-03-20 | Active | STUART |
| MARTIN COUNTY ORCHID SOCIETY, INC. | — | 713878 | 1967-12-29 | Active | STUART |
| MARTIN COUNTY PAIN CLINIC, PL | — | L05000030377 | 2005-03-28 | Active | STUART |
| MARTIN COUNTY PAPER COMPANY | — | F33335 | 1981-05-04 | Inactive | STUART |
| MARTIN COUNTY PARADE OF TURTLES, INC. | — | N01000003897 | 2001-05-29 | Inactive | STUART |
| MARTIN COUNTY PETROLEUM, INC. | — | G04031 | 1982-10-07 | Inactive | STUART |
| MARTIN COUNTY PLAZA ASSOCIATION, INC. | — | N51227 | 1992-10-09 | Active | Stuart |
| MARTIN COUNTY PLUMBING ASSOCIATION, INC. | — | N20291 | 1987-04-22 | Inactive | STUART |
| MARTIN COUNTY POLITICAL LEADERSHIP COUNCIL INC. | — | N12000011997 | 2012-12-28 | Inactive | STUART |
| MARTIN COUNTY PRESS, INC. | — | P24000056237 | 2024-09-03 | Active | STUART |
| MARTIN COUNTY PROBATION SRVICES, INC. | — | 767312 | 1983-03-04 | Inactive | STUART |
| MARTIN COUNTY PROFESSIONAL FIREFIGHTERS BUILDING FUND, INC. | — | N04000003862 | 2004-04-19 | Inactive | STUART |
| MARTIN COUNTY PROPERTIES LLC | — | L10000112083 | 2010-10-27 | Active | stuart |
| MARTIN COUNTY PROPERTIES, INC. | — | 589719 | 1978-10-12 | Inactive | STUART |
| MARTIN COUNTY PROPERTY SERVICES, INC. | — | G83230 | 1984-02-03 | Inactive | STUART |
| MARTIN COUNTY PUBLIC GUARDIAN, INC. | — | N04000001616 | 2004-02-11 | Inactive | STUART |
| MARTIN COUNTY QUILTERS INC | — | N07000001027 | 2007-01-30 | Active | Stuart |
| MARTIN COUNTY RAILS AND SCREENS, INC. | — | F50661 | 1981-10-22 | Inactive | STUART |
| MARTIN COUNTY RANCH COMMUNITY HOMEOWNERS ASSOCIATION, INC. | — | N03000006135 | 2003-07-17 | Active | Stuart |
| MARTIN COUNTY REALTORS OF THE TREASURE COAST, INC. | — | 732171 | 1975-03-17 | Active | Stuart |
| MARTIN COUNTY RESOURCES COMMITTEE, INC. | — | N23590 | 1987-11-23 | Inactive | STUART |
| MARTIN COUNTY RETIRED EDUCATIORS ASSOCIATION, INCORPORATED | — | N16426 | 1986-08-19 | Inactive | STUART |
| MARTIN COUNTY RETIRED EDUCATORS ASSOCIATION, INC | — | N26000003388 | 2026-03-05 | Active | STUART |
| MARTIN COUNTY RETIRED EDUCATORS ASSOCIATION, INC. | — | N07000001739 | 2007-02-08 | Inactive | Stuart |
| MARTIN COUNTY ROOFING COMPANY | — | J60795 | 1987-03-09 | Inactive | STUART |
| MARTIN COUNTY ROOFING LLC | — | L20000142356 | 2020-05-26 | Active | STUART |
| MARTIN COUNTY SCHOOL FOOD SERVICE ASSOCIATION, INC. | — | N08000011443 | 2008-12-19 | Active | STUART |
| MARTIN COUNTY SELF DEFENSE SUPPLY, INC. | — | P94000062506 | 1994-08-24 | Inactive | STUART |