| Kate Rose Academy CIC | Education | 2019 |
| Katelecom Ltd | Information & communication | 2019 |
| Kath Price Training and Consultancy Ltd | Professional & scientific | 2013 |
| Katie and Kayden Ltd | Hospitality | 2022 |
| Katie Jayne Limited | Wholesale & retail | 2015 |
| Kato Newcastle Limited | Hospitality | 2022 |
| Katsina Palm Limited | Information & communication | 2024 |
| Kavish Investments Ltd | Real estate | 2025 |
| Kavli Investments Limited | Professional & scientific | 2013 |
| Kavli UK Limited | Professional & scientific | 2013 |
| KAY3 Services NE Ltd | Hospitality | 2022 |
| KB Henry Logistics Limited | Transport & logistics | 2015 |
| KB Mortgage Solutions Ltd | Financial services | 2018 |
| KC Climate Ltd | Construction | 2025 |
| KC Transport (North East) Limited | Transport & logistics | 2013 |
| KCL Property Ltd | Real estate | 2025 |
| KD Coffee Limited | Hospitality | 2019 |
| KD PUB and Leisure GAS Ltd | Administrative & support | 2020 |
| KDB LT Energy Services Ltd | Professional & scientific | 2026 |
| Kears Properties Ltd | Real estate | 2024 |
| Kedson Ltd | Wholesale & retail | 2024 |
| Keegan Healthcare Limited | Health & social care | 2019 |
| Keelman Homes Limited | Real estate | 2009 |
| Keevo Ltd | Wholesale & retail | 2026 |
| Keith Hadden Tree Services Limited | Administrative & support | 2026 |
| Kelemen Consulting Ltd | Professional & scientific | 2025 |
| Kelly Covell Limited | Other services | 2018 |
| Kelly Offshore Services (North East) Ltd | Manufacturing | 2016 |
| Kelly's Heroes Private Tuition Ltd | Education | 2021 |
| Kennacq Limited | Financial services | 2020 |
| Kenneth Chappell Property Ltd | Manufacturing | 2021 |
| Kenneth James Limited | Wholesale & retail | 2003 |
| Kenruben Ltd | Wholesale & retail | 2025 |
| Kenzel Limited | Financial services | 2019 |
| Keren Trust | Other services | 2022 |
| Kerestir Ltd | Real estate | 2019 |
| Keser Torah Childcare Ltd | Education | 2025 |
| Keser Torah Early Years Ltd | Education | 2023 |
| Keser Torah Limited | Education | 2024 |
| Kesson Catering Ltd | Hospitality | 2026 |
| Keswick Estates Ltd | Real estate | 2025 |
| Keswick Ltd | Administrative & support | 2016 |
| Kettering Limited | Real estate | 2003 |
| Kevco Wholesale Limited | Wholesale & retail | 2008 |
| Kevin Angus and Sons Limited | Construction | 2017 |
| Kevin Parker Limited | Manufacturing | 2016 |
| Kevin Peden Limited | Construction | 2004 |
| Kevin Potts Design Limited | Information & communication | 2016 |
| Key North Group Ltd | Health & social care | 2015 |
| Keyfort Group Limited | Education | 2005 |
| Keystone Wellbeing Services C.I.C. | Education | 2020 |
| KEYWORKER4U Ltd | Administrative & support | 2022 |
| Kezzie Healthcare Ltd | Health & social care | 2020 |
| KF Realisations Limited | Wholesale & retail | 1998 |
| Kfky 131 Ltd | Extraterritorial | 2021 |
| Kfky 70 Ltd | Real estate | 2015 |
| Kfky 91 Ltd | Real estate | 2015 |
| Kfky Investments Ltd | Real estate | 2021 |
| Kfky Ltd | Professional & scientific | 2011 |
| Kgdesigngraph Ltd | Professional & scientific | 2023 |
| KGM Cleaning Services Limited | Administrative & support | 2022 |
| KGPROPERTY1 Ltd | Real estate | 2025 |
| KH SAS Limited | Other services | 2011 |
| Khaira Investment NE Ltd | Real estate | 2025 |
| Khaya NCL Ltd | Real estate | 2025 |
| Kheley Investments Ltd | Real estate | 2019 |
| Khera Foods Limited | Hospitality | 2025 |
| Khera North East Limited | Wholesale & retail | 2017 |
| KHM Investments Limited | Financial services | 2023 |
| Khomes Ltd | Construction | 2003 |
| Kianpharma Limited | Health & social care | 2015 |
| Kibblesworth Academy | Education | 2012 |
| Kick-Outs Ltd | Extraterritorial | 2026 |
| Kickpoint Limited | Real estate | 2002 |
| Kids Delights Ltd | Wholesale & retail | 2022 |
| Kidz R Fit Limited | Other services | 2012 |
| Kielder Forest Bathing Limited | Hospitality | 2023 |
| Kilcreggan Court Limited | Households | 2019 |
| Kimax (Timber Supplies) Limited | Wholesale & retail | 2002 |
| Kinetic Engineers (Leeds) Limited | Professional & scientific | 2010 |
| Kinetic Engineers Group Limited | Construction | 2009 |
| Kinetic Engineers Limited | Construction | 2007 |
| Kingdom Foods Limited | Wholesale & retail | 2008 |
| Kingdom of Catering Ltd | Hospitality | 2018 |
| Kingfisher Accounting Ltd | Professional & scientific | 2020 |
| Kingsgrove Property Limited | Real estate | 2022 |
| Kingsway House (Team Valley) Management Limited | Real estate | 2019 |
| Kinnersley Storage Ltd | Other services | 2020 |
| Kinz Bargains Ltd | Wholesale & retail | 2025 |
| Kiran Chippy Ltd | Hospitality | 2023 |
| Kirisi Ltd | Wholesale & retail | 2023 |
| Kirkham Enterprises Limited | Financial services | 2022 |
| Kirst AID ANP Ltd | Health & social care | 2019 |
| Kisama Ltd | Professional & scientific | 2012 |
| Kiso (Gateshead) Ltd | Wholesale & retail | 2019 |
| Kitchen Door Replacement Limited | Manufacturing | 2014 |
| Kitchen Granite and Quartz Worktops Limited | Manufacturing | 2026 |
| Kitchens & Bathrooms (North East) Ltd | Construction | 2025 |
| Kitchens Plus (SO) Ltd | Construction | 2021 |
| Kittu Limited | Information & communication | 2017 |