| Car Lease Shop Ltd | Administrative & support | 2017 |
| Carn Publishing Ltd. | Information & communication | 2017 |
| Carois Private Limited | Real estate | 2023 |
| Castarra Ltd | Construction | 2026 |
| Castle Convenience Store Limited | Wholesale & retail | 2021 |
| CC Granite Surfaces Ltd | Construction | 2025 |
| Ceiling Solutions Ltd | Construction | 2025 |
| Central Garage (Cumnock) LLP | | 2012 |
| Chameleon Arran LLP | | 2016 |
| Charlesfort Developments Ltd | Construction | 2015 |
| Charlesfort Holdings Ltd | Financial services | 2014 |
| Chili Tonight UK Limited | Hospitality | 2024 |
| Chris, Your MAN With a Van Ltd | Transport & logistics | 2026 |
| CIH Consulting Ltd | Information & communication | 2019 |
| Clan Tools & Plant Limited | Wholesale & retail | 1994 |
| Clark Electrical Ayrshire Limited | Construction | 2019 |
| Claymore Transport Solutions Ltd | Transport & logistics | 2024 |
| CNR Abnormal Load Services Ltd | Transport & logistics | 2025 |
| Codex Cranes Ltd | Administrative & support | 2025 |
| CONSULT55 Limited | Professional & scientific | 2022 |
| Cooper Farms Limited | Agriculture & fishing | 2021 |
| CPE Energy Limited | Construction | 2015 |
| Craft Spirits Limited | Extraterritorial | 2013 |
| Craig Wylie Ltd | Manufacturing | 2020 |
| Craiglang Properties Ltd | Construction | 2019 |
| Craigston Glen Ltd | Construction | 2026 |
| Craigston Property Ltd | Construction | 2026 |
| Crazy for Ruthie Ltd. | Manufacturing | 2022 |
| Crowntechdeals Ltd | Wholesale & retail | 2025 |
| Crucial Brands Holdings Limited | Wholesale & retail | 2014 |
| Crucial Drinks US Holdings Ltd | Wholesale & retail | 2017 |
| Crwye Solutions Ltd | Wholesale & retail | 2025 |
| Cuan Reach Limited | Professional & scientific | 2020 |
| Cumnock & District Leisure Group | Arts & recreation | 1999 |
| Cumnock Grocers Ltd | Wholesale & retail | 2023 |
| Cumnock Nails Limited | Other services | 2026 |
| Cumnock Newsagents Ltd | Wholesale & retail | 2025 |
| Cumnock Shiny Carwash Ltd | Wholesale & retail | 2022 |
| Cumnock Superstore Limited | Wholesale & retail | 2021 |
| Cumnock Sweets Limited | Manufacturing | 2024 |
| Cumnock Taxis Limited | Transport & logistics | 2025 |
| Curry Junction Drumchapel Ltd | Hospitality | 2020 |
| Curtainwise Soft Furnishings Limited | Financial services | 2026 |
| Cyclerate Limited | Professional & scientific | 2007 |
| D & a Morton Ltd | Agriculture & fishing | 2012 |
| D & C Robinson Ltd | Agriculture & fishing | 2024 |
| D & W Megamix Ltd. | Manufacturing | 2007 |
| D.B Avation Services Ltd | Manufacturing | 2026 |
| Dagmar Inns Limited | Hospitality | 2025 |
| Dalgliesh Training & Testing Services Ltd | Professional & scientific | 2025 |
| Datk Limited | Energy | 2018 |
| Datum Digital LLP | | 2008 |
| David's Gifts Ltd. | Manufacturing | 2014 |
| Delta European LP | | 2018 |
| DGG Engineering Limited | Professional & scientific | 2017 |
| Dispense and Design Group LLP | | 2026 |
| Dmcm Properties Ltd | Real estate | 2023 |
| Donald Hunter Architects Ltd | Professional & scientific | 2020 |
| Donsport Ltd | Wholesale & retail | 2022 |
| DPG (Cumnock) Ltd | Hospitality | 2024 |
| DRS Contracts Limited | Manufacturing | 2015 |
| DS Wetwall and Bathrooms Ltd | Construction | 2021 |
| Dumfries House Home Farm Limited | Agriculture & fishing | 2004 |
| Dylan Okane Exterior Cleaning Ltd | Administrative & support | 2025 |
| Echo Project Documentaries Limited | Information & communication | 2025 |
| Eco Homes Prestwick Ltd | Construction | 2024 |
| Ehret Business Venture Limited | Real estate | 2016 |
| Eight Holm Limited | Real estate | 2022 |
| Eiliyah & Zidan Limited | Wholesale & retail | 2017 |
| Elmfox Limited | Wholesale & retail | 2013 |
| Em&Em Bathroom Design and Installation Ltd | Construction | 2025 |
| Emcl Services Limited | Wholesale & retail | 2024 |
| Emergency One (U.K.) Limited | Administrative & support | 2007 |
| Emergency One Group Limited | Administrative & support | 2019 |
| Emergency One Limited | Extraterritorial | 1989 |
| Engaging Ltd | Administrative & support | 2025 |
| Engaging Weddings Ltd | Administrative & support | 2025 |
| Enhance Training Ltd | Education | 2020 |
| Eurasia Consultancy Limited | Professional & scientific | 2026 |
| Euroagg (Scotland) Limited | Wholesale & retail | 2022 |
| EXC Services Ltd | Construction | 2025 |
| Expert Roof Systems Ltd | Construction | 2023 |
| FGH Steel Erecting and Cladding Limited | Construction | 2025 |
| Financial & Capital (UK) Ltd | Financial services | 2025 |
| Fincap Limited | Financial services | 2025 |
| FJ Philanthropy Limited | Professional & scientific | 2015 |
| Flatroof & Roofline Experts M&S Contracts Limited | Construction | 2013 |
| Flintlock Holding 2.0 Ltd | Hospitality | 2023 |
| Force Fitness AYR Ltd | Arts & recreation | 2024 |
| Fossilfield Training Centre Ltd | Health & social care | 2022 |
| Foundation Solutions HV Ltd | Construction | 2015 |
| FOX Financial Planning Ltd | Professional & scientific | 2020 |
| Frasers Scotland LLP | | 2013 |
| Frge Consultancy & Coaching Ltd | Administrative & support | 2026 |
| Fshv Training Ltd | Education | 2023 |
| FST Plumbing & Heating Limited | Other services | 2008 |
| FWC Valeting Ltd | Administrative & support | 2026 |
| G & C Double Glazing Repair Limited | Other services | 2011 |
| G Watson Plant Repairs Ltd | Manufacturing | 2015 |
| Gates Psychological Services Ltd | Health & social care | 2024 |