| Kode Engineering Solutions Ltd | Information & communication | 2026 |
| Kokio Ltd | Wholesale & retail | 2022 |
| Kokko Holdings Limited | Professional & scientific | 2024 |
| Komati Limited | Information & communication | 2005 |
| Komgree Group Limited | Professional & scientific | 2018 |
| Kompli-Global Limited | Information & communication | 2016 |
| Konexxia Solutions Limited | Information & communication | 2019 |
| Konscia Ltd | Information & communication | 2019 |
| Koolrite Refrigeration & Air Conditioning Limited | Construction | 2007 |
| Kopi Management Ltd | Wholesale & retail | 2014 |
| Kosmos (UK) Ltd | Professional & scientific | 2003 |
| Kosmos Properties Limited | Real estate | 2016 |
| Kovi Carpets & Flooring Ltd | Wholesale & retail | 2024 |
| Kozee Sleep (Midlands) Limited | Manufacturing | 1986 |
| Kozee Sleep Direct Limited | Manufacturing | 2006 |
| Kozee Sleep Ltd | Manufacturing | 2004 |
| KP Estate Management Limited | Administrative & support | 2011 |
| KP Plus Limited | Other services | 2017 |
| KP Signature Limited | Health & social care | 2026 |
| KPA Holdings Limited | Financial services | 2024 |
| KPI Property Ltd | Real estate | 2022 |
| KPM Electrical Ltd | Construction | 2009 |
| Krahfam Global Ventures Ltd | Wholesale & retail | 2025 |
| Krdmck Ltd | Wholesale & retail | 2025 |
| Krep York Ltd | Hospitality | 2024 |
| Kreston Dunvale Limited | Extraterritorial | 2026 |
| Kresvis Trading Limited | Professional & scientific | 2007 |
| Kreuzung Ltd | Information & communication | 2017 |
| KRI19 Ltd | Administrative & support | 2026 |
| Kris Leeson Limited | Health & social care | 2012 |
| Krunchys Sandwichbar Limited | Hospitality | 2010 |
| KS Dentistry Limited | Health & social care | 2021 |
| KS Photobooths Ltd | Professional & scientific | 2024 |
| Ksag Engineering Consultants Ltd | Professional & scientific | 2016 |
| Ksda Limited | Real estate | 2021 |
| Ksivas Ltd | Wholesale & retail | 2024 |
| KSR Trust Ltd | Financial services | 2022 |
| KSS Media Ltd | Information & communication | 2014 |
| KST Associates Limited | Health & social care | 2024 |
| Kstar Associates Limited | Professional & scientific | 2013 |
| Kstar Development Limited | Real estate | 2024 |
| Kstar Group Limited | Professional & scientific | 2020 |
| KTH Health & Wellness Limited | Health & social care | 2010 |
| Ktrio Limited | Professional & scientific | 2025 |
| Kuba AI Ltd | Financial services | 2020 |
| Kube Recruitment Solutions Ltd | Administrative & support | 2013 |
| Kubus York Mini Market (2023) Limited | Wholesale & retail | 2023 |
| Kuchenstore Ltd | Wholesale & retail | 2024 |
| Kudos 365 Limited | Financial services | 1996 |
| Kudos Hair & Beauty Ltd | Other services | 2016 |
| Kuku Properties Limited | Real estate | 2024 |
| Kurd Corp Ltd | Information & communication | 2025 |
| Kurdish Touch Barber 1 Ltd | Other services | 2025 |
| Kush Locations Ltd | Information & communication | 2019 |
| Kutchenhaus Harrogate Ltd | Manufacturing | 2020 |
| Kval Systems Ltd | Information & communication | 2003 |
| KVR Retail NE Ltd | Wholesale & retail | 2026 |
| KW (York) Limited | Transport & logistics | 2016 |
| KW Strategy Ltd | Professional & scientific | 2025 |
| Kwestrian Ltd | Extraterritorial | 2008 |
| KWH (Hull) Limited | Construction | 2016 |
| KYG Ferry Holdings Ltd | Real estate | 2025 |
| Kyle Farming Limited | Agriculture & fishing | 2000 |
| Kyorn Ltd | Information & communication | 2007 |
| Kyoshi Consulting Ltd | Administrative & support | 2025 |
| Kyra-Women's Project | Education | 2013 |
| Kyria 2004 Ltd | Manufacturing | 2005 |
| Kyrix Technologies Limited | Information & communication | 2025 |
| Kyto Investments Ltd | Financial services | 2020 |
| KZ Dining Group Ltd | Hospitality | 2026 |
| KZW Associates Ltd | Professional & scientific | 2023 |
| Käthe Wohlfahrt Great Britain Limited | Wholesale & retail | 2015 |
| L & B Crockett Ltd | Wholesale & retail | 2024 |
| L & B Enterprises Limited | Wholesale & retail | 2004 |
| L & L Renovation Limited | Real estate | 2021 |
| L & M Homes Yorkshire Ltd | Construction | 2022 |
| L & P Properties (York) Limited | Real estate | 2017 |
| L & S Craven & Sons Limited | Agriculture & fishing | 2003 |
| L & V Vintage Limited | Wholesale & retail | 2025 |
| L E Pickles and SON Limited | Construction | 2002 |
| L G...Life,S Good ....Emergency Life Support Training Ltd | Professional & scientific | 2014 |
| L J Swan Property Limited | Real estate | 2025 |
| L Milburn Builders & Plasterers Limited | Construction | 2003 |
| L Philliskirk & SON Ltd | Water & waste | 2006 |
| L Skipsey Ltd | Health & social care | 2025 |
| L Wright Plumbing and Heating Limited | Construction | 2021 |
| L&D Lighting Solutions Ltd | Professional & scientific | 2019 |
| L&D Solutions Ltd | Professional & scientific | 2013 |
| L'Equip Europe Limited | Wholesale & retail | 2003 |
| L'Equip Limited | Wholesale & retail | 2003 |
| L'Equip UK Limited | Wholesale & retail | 2003 |
| L. Stringer and Family Ltd. | Information & communication | 2011 |
| L.E.T Services Ltd | Administrative & support | 2026 |
| L.I.K.E Electrical York Limited | Manufacturing | 2026 |
| L.R. Series Limited | Wholesale & retail | 2009 |
| L322 Services Limited | Professional & scientific | 2025 |
| L4RK Properties Limited | Real estate | 2023 |
| LA Cucina Ltd | Manufacturing | 2024 |
| LA Maruca Ltd | Wholesale & retail | 2023 |
| LA Morra Limited | Real estate | 2021 |