| Holms Fishing Company Limited | Agriculture & fishing | 1993 |
| Home Office Design Limited | Wholesale & retail | 2004 |
| Home Sales Fast Ltd | Real estate | 2022 |
| Homesure Properties Limited | Real estate | 2016 |
| Hoose and Hame Ltd | Real estate | 2026 |
| Hopkins of Troon Limited | Wholesale & retail | 1991 |
| Horse and Pet Warehouse Limited | Wholesale & retail | 2012 |
| Horton Consulting Services Ltd | Professional & scientific | 2026 |
| Hospitality Consultants AYR Ltd | Professional & scientific | 2023 |
| House Matters Chimney Services Ltd | Administrative & support | 2022 |
| House Matters Ltd | Administrative & support | 2022 |
| HP 154 Ltd | Hospitality | 2025 |
| HR04 Ltd | Real estate | 2023 |
| HR20 Ltd | Real estate | 2026 |
| HRB Holdings Limited | Hospitality | 2019 |
| HSK Music Limited | Wholesale & retail | 2010 |
| HT Residential Ltd | Administrative & support | 2012 |
| HUG a MUG Takeaway LP | | 2022 |
| Hugh Blane & SON Limited | Construction | 2014 |
| Hugh Strain & Sons Ayrshire Scotland Limited | Manufacturing | 2025 |
| Hunter Kingsley Ltd | Wholesale & retail | 2018 |
| Huxtable Design and Build Ltd | Construction | 2016 |
| Hy-Performance Club Ltd | Arts & recreation | 2023 |
| Hybrid Tanning Ltd | Other services | 2022 |
| Hyperspec.Talent Ltd | Administrative & support | 2025 |
| I-Tek Repair Ltd | Manufacturing | 2026 |
| Iain a Andrew Ltd | Construction | 2024 |
| IAN Mccubbin Decorators Limited | Construction | 2021 |
| IAN Robertson Golf Ltd | Wholesale & retail | 2017 |
| Iannotti Bros (Property) Limited | Construction | 1978 |
| Iannotti Bros. Limited | Administrative & support | 1978 |
| Icatu Business LP | | 2017 |
| ICR Wallace Ltd | Other services | 2025 |
| ID Dawson Ltd | Mining & quarrying | 2025 |
| Identification Technologies (Scotland) Limited | Wholesale & retail | 1992 |
| Identiqrypt Ltd | Professional & scientific | 2026 |
| Idhanya Ltd | Wholesale & retail | 2025 |
| IDP Services Ltd | Professional & scientific | 2015 |
| Ikonic Print Ventures Ltd | Wholesale & retail | 2020 |
| Ilsey Sales LP | | 2016 |
| Im-Press Promotions (AYR) Ltd. | Wholesale & retail | 2000 |
| Imaginocity Limited | Education | 2019 |
| IMC Isla Property Limited | Real estate | 2016 |
| IMPACT54 Limited | Professional & scientific | 2015 |
| Implamax LP | | 2015 |
| Indigo Nails LAB Ltd | Wholesale & retail | 2015 |
| INDIUM2 Ltd | Professional & scientific | 2020 |
| Indtel Services Limited | Professional & scientific | 2016 |
| Infotranche Ltd | Information & communication | 2025 |
| Ingredients Go Ltd | Hospitality | 2024 |
| Inky.Studio Ltd | Information & communication | 2026 |
| Innoisland Ltd | Education | 2025 |
| Innovu Marketing Limited | Wholesale & retail | 2023 |
| Inquatrum LP | | 2017 |
| Inside Outside Ltd | Construction | 2021 |
| Inside Outside Properties Ltd | Real estate | 2022 |
| Instaspect Limited | Professional & scientific | 1987 |
| Instinctive HR Ltd | Administrative & support | 2019 |
| Instyle Properties Limited | Real estate | 2001 |
| Integra Building Contractors Ltd | Construction | 2018 |
| Interference Pattern Limited | Information & communication | 2008 |
| International Holdings Management Limited | Health & social care | 2011 |
| Inverclyde Investment Company Limited | Professional & scientific | 2009 |
| Invictus Heart Limited | Information & communication | 2017 |
| Ioan Ciobanu Welding Limited | Manufacturing | 2012 |
| Irvine-Thomson Limited | Information & communication | 2016 |
| Isla's Property Company Limited | Real estate | 2008 |
| IWL Electrical Limited | Construction | 2016 |
| IWM Electrical Limited | Manufacturing | 2020 |
| IWM Property Limited | Households | 2021 |
| Izolur Distribution LP | | 2014 |
| J & a Forecourt Services Limited | Professional & scientific | 2006 |
| J & B Properties (Scotland) Ltd | Real estate | 2015 |
| J & D Services (Scotland) Ltd. | Mining & quarrying | 2005 |
| J & E Y Murphy Ltd. | Wholesale & retail | 2008 |
| J Arthur Consulting Ltd | Professional & scientific | 2019 |
| J C Fergusson Ltd | Construction | 2017 |
| J H Commercials Ltd | Wholesale & retail | 2018 |
| J Martin Properties Ltd | Real estate | 2017 |
| J Mcinnes Joinery Ltd | Construction | 2014 |
| J R Clark Trading Ltd | Extraterritorial | 2018 |
| J.A. Alexander & SON Ltd. | Transport & logistics | 1997 |
| J.G.L. Roofing Ltd. | Construction | 1998 |
| Jacada Holdings Ltd | Real estate | 2019 |
| Jack Lamb (Agricultural Merchant) Ltd. | Wholesale & retail | 2011 |
| Jadesa Joinery Ltd | Construction | 2021 |
| JAG Property Ltd | Real estate | 2016 |
| Jaggar Properties Ltd | Real estate | 2025 |
| Jake Mckechan Ltd | Construction | 2016 |
| Jamawal Two Limited | Real estate | 2021 |
| James Craig (Farms) Limited | Administrative & support | 1988 |
| James Craig Holdings Limited | Financial services | 2021 |
| James Craig Limited | Administrative & support | 1906 |
| James Craig Marts Holdings Limited | Financial services | 2021 |
| James Craig Marts Limited | Financial services | 2021 |
| James Mccririck | | 1998 |
| James of Diamond International Limited | Wholesale & retail | 2008 |
| James Stirling Engineering Ltd | Professional & scientific | 2024 |
| James-Martin Property Ltd | Real estate | 2025 |
| Jamie Wilson Ventilation Ltd | Manufacturing | 2017 |