| James Farren Limited | Construction | 2014 |
| James Guthrie & Company LLP | | 2008 |
| James Guthrie Trustee Company Limited | Extraterritorial | 2014 |
| James ORR Engineering Limited | Extraterritorial | 2012 |
| James Ronald Transport Limited | Transport & logistics | 2016 |
| Jamie Bell Holdings Limited | Financial services | 2021 |
| Jamie Green Joinery Ltd | Manufacturing | 2024 |
| Jamieson & Adams Ltd | Health & social care | 2022 |
| Jams Property Services Ltd | Real estate | 2014 |
| JAN Hydro Co Ltd | Professional & scientific | 2014 |
| Jane Ballantyne Limited | Financial services | 2006 |
| Jaybee Venture Holdings Ltd | Hospitality | 2026 |
| JAZ Retail Ltd | Wholesale & retail | 2021 |
| JB Electrics Limited | Construction | 2015 |
| JC Contracts Ayrshire Limited | Other services | 2017 |
| JCM Online Ltd | Administrative & support | 2023 |
| JCN & Sons Ltd | Other services | 2016 |
| JD ARB Ltd | Agriculture & fishing | 2025 |
| JD Brickwork and Groundworks Ltd | Construction | 2026 |
| JD Tiling and Plastering Solutions Limited | Construction | 2021 |
| JDC Landscaping Limited | Construction | 2025 |
| JEG Kilmarnock Limited | Wholesale & retail | 2018 |
| JEM Property Sales Ltd | Real estate | 2020 |
| JEN Seafood Ltd | Wholesale & retail | 2024 |
| Jenclean Ltd | Administrative & support | 2010 |
| Jenny Laurens Therapist Ltd | Health & social care | 2025 |
| JES Property Solutions Ltd | Real estate | 2026 |
| Jetsetter Travels Ltd | Administrative & support | 2023 |
| Jewel Stone Ltd | Hospitality | 2026 |
| JFS Kilmarnock Ltd | Wholesale & retail | 2026 |
| Jgarden Hurlford Ltd | Hospitality | 2025 |
| JGARDEN32168 Limited | Hospitality | 2024 |
| JIM Caldwell Limited | Construction | 2014 |
| JIM Mcpherson (Coaching and Consulting) Ltd | Professional & scientific | 2022 |
| Jimjamthevanman Ltd | Wholesale & retail | 2025 |
| Jirvine Aero Services Ltd | Manufacturing | 2025 |
| Jjsc Investment Ltd | Financial services | 2025 |
| JK Construction (Builders) Limited | Construction | 2015 |
| JK Surveyors Ltd | Professional & scientific | 2026 |
| Jkdp Ltd. | Professional & scientific | 2009 |
| JLC Consultants Limited | Professional & scientific | 2012 |
| JLJ Groundworks Ltd | Construction | 2022 |
| JMC Dietetics Limited | Health & social care | 2025 |
| Jmcg Fabrication Ltd | Construction | 2025 |
| Jnft Holdings Ltd | Financial services | 2022 |
| Joanne Mclean Consulting Ltd | Administrative & support | 2017 |
| Jodie Manson Coaching Limited | Education | 2022 |
| JOE Bloggs Pipefitters & Co Ltd | Construction | 2018 |
| JOE Mcpherson Digger & Groundworks Ltd | Administrative & support | 2021 |
| John Alexander Engineering Ltd | Professional & scientific | 2011 |
| John B Rail Limited | Construction | 2015 |
| John K Ramage Decorators Limited | Construction | 2025 |
| John O'Connor & SON Funeral Home Limited | Other services | 2020 |
| John O'Connor Funeral Directors Limited | Other services | 2020 |
| John Ritchie (Christian Publisher) Ltd | Information & communication | 2012 |
| John Ritchie (Kilmarnock) Ltd | Extraterritorial | 2012 |
| John Ritchie Limited | Wholesale & retail | 2011 |
| John Short & Sons (Bakers) Limited | Extraterritorial | 1945 |
| John Smillie Property Rentals Ltd | Real estate | 2026 |
| John Smith & Sons (Kilmaurs Mains) Limited | Agriculture & fishing | 2011 |
| John Street Properties (Oban) Limited | Real estate | 2014 |
| John Stuart Thom Limited | Professional & scientific | 2014 |
| John W Short Limited | Manufacturing | 2010 |
| Jonick Homes Ltd | Professional & scientific | 2022 |
| Jonick Limited | Real estate | 2016 |
| Jonick Wexford Limited | Construction | 2018 |
| Jougs Brewing Ltd | Manufacturing | 2025 |
| JPH Joinery Services Ltd | Construction | 2021 |
| JPS Utilities (Scot) Ltd | Construction | 2015 |
| JQ Project Services Ltd | Professional & scientific | 2025 |
| JR Fashion PVT Ltd | Wholesale & retail | 2023 |
| JR Martial Arts Ltd | Arts & recreation | 2022 |
| JRD Partnership (Garnock Valley) Ltd | Professional & scientific | 2017 |
| JRD Partnership (Payroll Bureau) Ltd. | Administrative & support | 2017 |
| JRS Projects Ltd | Manufacturing | 2018 |
| JSR Legal Ltd | Professional & scientific | 2023 |
| JTR Automation Limited | Professional & scientific | 2020 |
| Julie Mcintosh Ltd | Professional & scientific | 2016 |
| Julie Smith Equestrian Limited | Agriculture & fishing | 2005 |
| Jungle Madness Limited | Arts & recreation | 2011 |
| Just ASK Home Hardware Ltd | Wholesale & retail | 2021 |
| Just ME Hairdressing Limited | Other services | 2013 |
| JV Properties (Scotland) Ltd. | Real estate | 2012 |
| JW Commercial Management Ltd | Professional & scientific | 2020 |
| JW Health & Fitness Ltd | Arts & recreation | 2014 |
| JYM Property Limited | Real estate | 2024 |
| K & M Fuels Limited | Real estate | 2000 |
| K and K Services ( Ayrshire ) Ltd | Professional & scientific | 2023 |
| K Bain Properties Limited | Real estate | 2024 |
| K E Brewster Ltd | Financial services | 2024 |
| K Haugland Consultancy Ltd | Professional & scientific | 2017 |
| K Robinson Consultancy Ltd | Information & communication | 2025 |
| K W Roofing and Cladding Limited | Construction | 2017 |
| K Z Enterprises Limited | Real estate | 2002 |
| K&C Dancetech UK CIC | Education | 2025 |
| K&G Stewart Holdings Limited | Financial services | 2023 |
| K&Jautomotiverepairs Ltd | Professional & scientific | 2022 |
| K&R Homes (Scotland) Ltd | Construction | 2024 |
| K-Mac Homes Ltd | Construction | 2018 |
| K-Vell Ltd | Wholesale & retail | 2021 |