| Jupiter Driver Hire Ltd | Transport & logistics | 2015 |
| Just Realty Limited | Real estate | 2018 |
| Just Safe Services Ltd | Professional & scientific | 2024 |
| JW Budd Ltd | Arts & recreation | 2016 |
| JWB Investment Properties Limited | Real estate | 2019 |
| JWK Plasterers Ltd | Construction | 2019 |
| K and C Living Limited | Real estate | 2023 |
| K D Events & Catering Ltd | Hospitality | 2020 |
| K O Cabs Ltd | Transport & logistics | 2024 |
| K Retail Shop Ltd | Wholesale & retail | 2023 |
| K Williams Construction Ltd | Construction | 2015 |
| K1RBY (Wales) Limited | Construction | 2019 |
| K3 Mini Market Ltd | Wholesale & retail | 2024 |
| K9 on the Run Ltd | Agriculture & fishing | 2023 |
| K9 Resort Ltd | Agriculture & fishing | 2023 |
| Kaixinming Limited | Wholesale & retail | 2023 |
| Kaizen Instrumentation Services Limited | Construction | 1999 |
| Kalomans Biotech Ltd | Wholesale & retail | 2024 |
| Kamsana Ltd | Wholesale & retail | 2026 |
| Kappakonsult Resources and Services Ltd | Professional & scientific | 2020 |
| Karabar Capital Limited | Real estate | 2019 |
| Karabar Commercial Properties Limited | Real estate | 2016 |
| Karabar Homes Ltd | Real estate | 2026 |
| Karuana Ltd | Wholesale & retail | 2022 |
| Kash Properties Limited | Extraterritorial | 2014 |
| Kathrens Energy Efficient Build Systems Limited | Construction | 2011 |
| Kathrens Energy Limited | Construction | 2022 |
| Kathrens Holdings Limited | Real estate | 2007 |
| KAY Morgan the Greyhound PUB Ltd | Hospitality | 2010 |
| KB Nexus Living Ltd | Real estate | 2024 |
| KBR Motorcycles Limited | Wholesale & retail | 2021 |
| KD Property Ltd | Real estate | 2019 |
| Kdpublishingandco Ltd | Wholesale & retail | 2026 |
| Keden Properties Ltd | Real estate | 2020 |
| Keiron White Rail Services Limited | Construction | 2016 |
| Keith Bundy Heating Limited | Construction | 2014 |
| Keith Evans Plant & Building Limited | Construction | 2019 |
| Keltrose Virtual Partner Limited | Administrative & support | 2025 |
| Kenneth Lewis Partnership Limited | Professional & scientific | 2009 |
| Kenyon SAX Limited | Professional & scientific | 2008 |
| Kepler Automation Co., Ltd. | Extraterritorial | 2019 |
| Keychron Technology Ltd | Wholesale & retail | 2024 |
| Keystone Fencing Limited | Construction | 2026 |
| Keystores Rhydfelin Limited | Wholesale & retail | 2019 |
| KFJ Properties Ltd | Real estate | 2021 |
| Khaleesi Ltd | Wholesale & retail | 2018 |
| Kilex Rental Properties Ltd | Real estate | 2020 |
| Kilex Serviced Accommodation Ltd | Hospitality | 2020 |
| Kimbaly Homes Limited | Real estate | 2026 |
| KIN Filter Engineering Co., Limited | Professional & scientific | 2008 |
| Kingshine Industrial Co., Ltd | Professional & scientific | 2007 |
| Kissio Ltd | Wholesale & retail | 2024 |
| KJD E-Shop Ltd | Wholesale & retail | 2021 |
| KJP Autoparts Ltd | Wholesale & retail | 2017 |
| KJP Property Holding Ltd | Real estate | 2019 |
| KK Fire Protection Limited | Construction | 2022 |
| KK Group Investment Ltd | Real estate | 2023 |
| KK Quality Cleaning Ltd | Administrative & support | 2021 |
| KKM Online Limited | Wholesale & retail | 2018 |
| Klass Kabs Ltd | Transport & logistics | 2010 |
| Klean + Tidy 4 U Ltd | Administrative & support | 2026 |
| Klmn Agile Limited | Professional & scientific | 2019 |
| KME Social Work Assessments Ltd | Health & social care | 2026 |
| Kmlj Solutions Limited | Administrative & support | 2023 |
| KMR Rail Services Ltd | Construction | 2019 |
| Knight Archers Ltd | Wholesale & retail | 2021 |
| Knights Dental Group Limited | Health & social care | 2023 |
| Knotweedbusters Limited | Administrative & support | 2015 |
| Knowles Property Sales Ltd | Real estate | 2026 |
| Kookville Ltd | Wholesale & retail | 2023 |
| Korbuild Limited | Construction | 2004 |
| Kore Electrical Ltd | Construction | 2018 |
| Kormad Holdings Limited | Financial services | 2023 |
| Krishan Service Station Ltd | Wholesale & retail | 2017 |
| KS SRA Ltd | Administrative & support | 2024 |
| KSP Gardens and Grounds Maintenance Ltd | Administrative & support | 2021 |
| Kudos Contract Finishes Ltd | Construction | 2018 |
| Kwesoftware Limited | Information & communication | 2019 |
| Kynto Ltd | Wholesale & retail | 2026 |
| L & N Property Limited | Administrative & support | 2001 |
| L JAY Transport Ltd | Transport & logistics | 2025 |
| L&B Drylining Limited | Construction | 2024 |
| L&L Taverns Ltd | Hospitality | 2024 |
| L'Imbrunire & Aurora Ltd Co., Ltd | Wholesale & retail | 2024 |
| L. N. W. Brickwork Limited | Construction | 2017 |
| L.P. Drylining and Plasterers Limited | Wholesale & retail | 1992 |
| L.R.Ala Limited | Public administration | 2018 |
| L3 Projects Limited | Real estate | 2026 |
| Lakeside Herdwicks Limited | Agriculture & fishing | 2025 |
| Lanpark Property Ltd | Households | 2025 |
| Lanwood Construction Limited | Construction | 2007 |
| Lanzak Limited | Wholesale & retail | 2010 |
| Larchwing Limited | Agriculture & fishing | 1987 |
| Laser Fire & Security Ltd | Administrative & support | 2010 |
| Laser Interior & Exterior Ltd | Construction | 2021 |
| Laser MEG Limited | Health & social care | 2023 |
| Laser Wire Solutions Limited | Manufacturing | 2011 |
| Laudit Ltd | Administrative & support | 2020 |
| Laura Jones Translation Ltd. | Professional & scientific | 2017 |
| Laver Group Limited | Construction | 1981 |