| Kathryn Gordon Limited | Health & social care | 2011 |
| KAZ Property Ltd | Real estate | 2024 |
| Kebresh Ltd | Real estate | 2026 |
| Kegs for YOU Ltd | Wholesale & retail | 2019 |
| Kehinde Ahmed Ltd | Extraterritorial | 2023 |
| Kela Group Limited | Real estate | 2025 |
| KEN Stewart Consultancy Ltd | Professional & scientific | 2014 |
| Kenny Homes Holding Company | Financial services | 2024 |
| Kenzo Design and Build Ltd | Manufacturing | 2023 |
| Kero Business Solutions Ltd | Information & communication | 2017 |
| Kero Kode Solutions Ltd | Information & communication | 2026 |
| Kerry Bell Ltd | Health & social care | 2026 |
| Kerry House Farms Limited | Agriculture & fishing | 2022 |
| Khayber Glengormley Ltd | Hospitality | 2023 |
| Kids Club Crew Ltd | Wholesale & retail | 2025 |
| Kiernan’S Food Ingredients (UK) Limited | Wholesale & retail | 2023 |
| Kilcarn Limited | Extraterritorial | 2009 |
| Kilco (International) Ltd | Manufacturing | 1953 |
| Killeter Limited | Real estate | 1986 |
| KIN 11 Takeaway Ltd | Hospitality | 2021 |
| Kingscourt Bricks Limited | Professional & scientific | 1985 |
| Kingscourt Clay Products Limited | Extraterritorial | 2010 |
| Kirkhill Developments Ltd | Construction | 2017 |
| Kirsty Mick Tattoos Ltd | Arts & recreation | 2020 |
| Kitchen Equipment (Northern Ireland) Limited | | 1989 |
| Kitchen POD Hire Ltd | Administrative & support | 2021 |
| Kitguru Limited | Information & communication | 2011 |
| KLS Digital Ltd | Information & communication | 2026 |
| KM Marine Services Ltd | Professional & scientific | 2022 |
| Knight Design Engineering Limited | Manufacturing | 2004 |
| Knightsbridge Construction Services Ltd | Professional & scientific | 2025 |
| Knockmany Property Limited | Real estate | 2024 |
| Koko Asian Street Food Ltd | Extraterritorial | 2024 |
| Koko Eats Monkstown Ltd | Hospitality | 2026 |
| Krest Entertainment Ltd | Arts & recreation | 2022 |
| Kromax Media Limited | Information & communication | 2016 |
| Kudos Window Systems (NI) Ltd | Construction | 2025 |
| Kulea Holdings Ltd | Wholesale & retail | 2026 |
| Kyle & Graham Ltd | Manufacturing | 1995 |
| Kyle Insurance and Financial Services LLP | | 2020 |
| Kylo Design Ltd | Professional & scientific | 2020 |
| Kyra ORR Interiors Limited | Professional & scientific | 2022 |
| Lace Labs Shoelaces LLP | | 2024 |
| Lagan Airports Limited | Extraterritorial | 2010 |
| Lagan Asphalt (UK) Ltd | Construction | 2014 |
| Lagan Asphalt Group Limited | Professional & scientific | 2009 |
| Lagan Cement Limited | Extraterritorial | 1988 |
| Lagan Cement Products Limited | Extraterritorial | 1987 |
| Lagan Properties (1970) Limited | Hospitality | 1970 |
| Lagan Whitemountain Limited | Extraterritorial | 2013 |
| Laganshire Ltd | Wholesale & retail | 2021 |
| Lagst (Scotland) Ltd | Professional & scientific | 2007 |
| Lalor Ltd | Health & social care | 2023 |
| Lamp Source Ltd | Wholesale & retail | 2013 |
| Langley Enterprises Ltd | Hospitality | 2016 |
| Lany Eawa | Financial services | 2025 |
| Lara Goodall Consulting Ltd | Professional & scientific | 2014 |
| Larkin Consultants Ltd | Administrative & support | 2015 |
| Laurice RN Ltd | Administrative & support | 2025 |
| Lavery & Haughian Limited | Wholesale & retail | 2004 |
| Law & Co Financial Management Ltd | Professional & scientific | 2024 |
| LB Property & Investments Limited | Real estate | 2025 |
| LD Catering Ltd | Wholesale & retail | 2018 |
| LD Interiors Limited | Manufacturing | 2024 |
| LE PUG Ltd | Other services | 2021 |
| Leafield Management Company Ltd | Real estate | 2009 |
| Lease for Living Ltd | Real estate | 2024 |
| Legal Business Solutions Limited | Administrative & support | 2008 |
| Legal Costing (NI) Ltd | Professional & scientific | 2010 |
| Legatia Ltd | Information & communication | 2020 |
| Lenamore Medical Limited | Health & social care | 2019 |
| Leonard and Sara Ltd | Health & social care | 2024 |
| Let's Talk Online Psychology Ltd | Health & social care | 2024 |
| Level 91 Entertainment Ltd | Information & communication | 2017 |
| Level Demolition Ltd | Construction | 2023 |
| Lewis Hall Medical Limited | Health & social care | 2019 |
| Lewis Mills Financial Ltd | Financial services | 2024 |
| Lexigram Ltd | Education | 2025 |
| LH Leisureland Ltd | Hospitality | 2010 |
| Liam Carroll Refrigerated and DRY Freight Haulage | | 2006 |
| Libertas Solutions Limited | Information & communication | 2002 |
| Life Beyond Diagnosis NI CIC | Health & social care | 2026 |
| Light N' UP Ltd | Professional & scientific | 2011 |
| Lighthouse Catering Ltd | Hospitality | 2025 |
| Lily Mays Cafe Ltd | Hospitality | 2024 |
| Lin's Garden Abbey Ltd | Hospitality | 2026 |
| Lionslighting Limited | Health & social care | 2025 |
| Lisheen Corporate Limited | Professional & scientific | 2015 |
| Lismore Estates Limited | Households | 2022 |
| Litton Estates Ltd | Real estate | 1966 |
| Lizhi Tang Limited | Real estate | 2024 |
| LKB Properties and Investments Ltd | Real estate | 2023 |
| LL Copyright and Media Services Limited | Other services | 2002 |
| LLB NI Property Ltd | Real estate | 2023 |
| LM Design & Build - Contracts & Landscaping Ltd | Construction | 2023 |
| Lock & Key Property Ltd | Real estate | 2025 |
| Loft Trading Limited | Manufacturing | 2013 |
| Logan Automotive Finance Limited | Financial services | 1985 |
| Loinnir House Ltd | Arts & recreation | 2026 |
| Lola Lemon Limited | Wholesale & retail | 2025 |