| MARTIN COUNTY CONSERVATION ALLIANCE, INC. | — | N97000000519 | 1997-01-27 | Active | STUART |
| MARTIN COUNTY CONSULTANTS, INC. | — | P96000057840 | 1996-07-10 | Inactive | STUART |
| MARTIN COUNTY CROSS COUNTRY CORPORATION | — | N16000000593 | 2016-01-19 | Inactive | STUART |
| MARTIN COUNTY CURRENTS LLC | — | L14000106335 | 2014-07-03 | Active | STUART |
| MARTIN COUNTY CUSTOM POOLS, INC. | — | 420874 | 1973-03-09 | Inactive | STUART |
| MARTIN COUNTY DESTINATION MARKETING CORPORATION | — | N06000008480 | 2006-08-11 | Inactive | STUART |
| MARTIN COUNTY DISTRICT 2 VOLUNTEER FIRE DEPARTMENT, INC. | — | 743378 | 1978-06-26 | Inactive | STUART |
| MARTIN COUNTY ELECTRIC, INC. | — | P94000001395 | 1994-01-03 | Inactive | STUART |
| MARTIN COUNTY ENRICHMENT FOUNDATION, INC. | — | N98000000680 | 1998-02-05 | Inactive | STUART |
| MARTIN COUNTY ENVIRONMENTAL RECYCLING CENTER, INC. | — | K23000 | 1988-05-09 | Inactive | STUART |
| MARTIN COUNTY ESTATE PLANNING COUNCIL, INC. | — | N99000004968 | 1999-08-16 | Active | STUART |
| MARTIN COUNTY FAIR ASSOCIATION, INC. | Arts and entertainment | N18000012258 | 2018-11-16 | Active | STUART |
| MARTIN COUNTY FAIR PRACTICES IN GOVERNMENT, INC. | — | P07000121474 | 2007-11-07 | Inactive | STUART |
| MARTIN COUNTY FARM BUREAU, INC. | — | N12000009469 | 2012-09-28 | Active | STUART |
| MARTIN COUNTY FARM BUREAU, LAA | — | 790631 | 1950-06-29 | Inactive | STUART |
| MARTIN COUNTY FARMS, LLC | — | L08000054094 | 2008-05-30 | Active | Stuart |
| MARTIN COUNTY FEDERATION FOR THE FINE ARTS, INC. | — | N15574 | 1986-06-24 | Inactive | STUART |
| MARTIN COUNTY FEDERATION OF HOME AND PROPERTY OWNERS ASSOCIATIONS, INC. | — | N12458 | 1985-12-10 | Inactive | STUART |
| MARTIN COUNTY FIRE RESCUE HONOR GUARD INC. | — | N04000004770 | 2004-05-14 | Inactive | STUART |
| MARTIN COUNTY FIREFIGHTERS ASSOC. INC. | — | N16000003586 | 2016-04-07 | Active | STUART |
| MARTIN COUNTY FIREFIGHTERS BENEVOLENT ASSOCIATION, INC. | — | N21000011451 | 2021-09-28 | Active | STUART |
| MARTIN COUNTY FLORIDA ARES/RACES, INC. | — | N99000000656 | 1999-02-02 | Active | STUART |
| MARTIN COUNTY FOREVER LLC | — | L23000111593 | 2023-03-02 | Active | STUART |
| MARTIN COUNTY FOUNDATION FOR CITIZENS WITH DISABILITIES, INC. | — | N98000002255 | 1998-04-17 | Inactive | STUART |
| MARTIN COUNTY FUTURE GROUP, INC. | — | N07000011366 | 2007-11-26 | Inactive | STUART |
| MARTIN COUNTY GARAGE, LLC | — | L05000052665 | 2005-05-26 | Inactive | STUART |
| MARTIN COUNTY GENEALOGICAL SOCIETY, INC. | — | N97000000004 | 1996-12-26 | Active | STUART |
| MARTIN COUNTY GIRLS FASTPITCH, INC. | — | N09000005520 | 2009-06-05 | Inactive | STUART |
| MARTIN COUNTY GIRLS LACROSSE CLUB, INC. | — | N01000001708 | 2001-03-07 | Inactive | STUART |
| MARTIN COUNTY GLASS INC. | — | H20696 | 1984-09-12 | Inactive | STUART |
| MARTIN COUNTY GOLF AND COUNTRY CLUB, INC. | — | 745757 | 1979-01-30 | Inactive | STUART |
| MARTIN COUNTY GOLF CARTS, INC. | — | 480357 | 1975-07-10 | Inactive | STUART |
| MARTIN COUNTY GOLF SCHOLARSHIPS, INC. | — | N02000 | 1984-03-16 | Inactive | STUART |
| MARTIN COUNTY HAND REHABILITATION CENTER, INC. | — | M59240 | 1987-09-17 | Inactive | STUART |
| MARTIN COUNTY HEALTHY START COALITION, INC. | — | N49152 | 1992-06-01 | Active | STUART |
| MARTIN COUNTY HIGH SCHOOL DRAMA BOOSTERS, INC | — | N14000009701 | 2014-10-20 | Inactive | STUART |
| MARTIN COUNTY HIGH-SCHOOL OPUS BOOSTERS, INC. | — | N14000002052 | 2014-03-03 | Active | STUART |
| MARTIN COUNTY HOLDINGS LLC | — | L21000183404 | 2021-04-20 | Active | STUART |
| MARTIN COUNTY HOME WATCH LLC | — | L26000241425 | 2026-04-29 | Active | STUART |
| MARTIN COUNTY INSURANCE, INC. | — | G47879 | 1983-07-08 | Inactive | STUART |
| MARTIN COUNTY INTERAGENCY COALITION, INC. | — | N94000000704 | 1994-02-10 | Active | STUART |
| MARTIN COUNTY INVESTMENT, INC. | — | 687146 | 1980-09-10 | Inactive | STUART |
| MARTIN COUNTY IRRIGATION, INC. | — | H36985 | 1985-01-07 | Inactive | STUART |
| MARTIN COUNTY JAGUARS YOUTH FOOTBALL, INC | — | N15000009986 | 2015-10-13 | Active | STUART |
| MARTIN COUNTY JANITORIAL SUPPLY, LLC | — | M18000003472 | 2018-04-09 | Active | STUART |
| MARTIN COUNTY JUNIOR GOLF ASSOCIATION, INC. | — | N93000002296 | 1993-05-19 | Inactive | STUART |
| MARTIN COUNTY KARTING ASSOCIATION, INC. | — | N00000003779 | 2000-06-05 | Inactive | STUART |
| MARTIN COUNTY LACROSSE CLUB, INC. | — | N02000009141 | 2002-11-18 | Inactive | STUART |
| MARTIN COUNTY LADY LUCK PROTECT THE MANATEE CLUB, INC. | — | N17483 | 1986-10-24 | Inactive | STUART |
| MARTIN COUNTY LAND CONSERVATION TRUST LLC | — | L26000247640 | 2026-05-04 | Active | STUART |