| Joss Cade Plumbing & Heating Limited | Construction | 2021 |
| Jpfg Solutions Ltd | Wholesale & retail | 2019 |
| JPH Electrical Services Ltd | Construction | 2006 |
| JR Marsh Properties Ltd | Real estate | 2025 |
| JS Transport Management Services Limited | Professional & scientific | 2015 |
| JSE Systems Limited | Agriculture & fishing | 2009 |
| JSM Blossom Properties Ltd | Real estate | 2025 |
| Juice-E-Vaporium Limited | Wholesale & retail | 2016 |
| Jukebox Early-Learning Ltd | Arts & recreation | 2021 |
| Julian West Limited | Financial services | 2014 |
| Julianos A&F Limited | Hospitality | 2024 |
| Just a Bank Limited | Administrative & support | 2002 |
| Just Delivers Ltd | Transport & logistics | 2025 |
| Just Gents Barbers Ltd | Other services | 2024 |
| Just Imagine Toys Ltd | Wholesale & retail | 2019 |
| Justified Fire and Security Ltd | Administrative & support | 2022 |
| Justin Haynes Painters & Decorators Limited | Construction | 2019 |
| Justyna Wójtowicz Ltd | Professional & scientific | 2022 |
| JWR Supply Chain Services Limited | Professional & scientific | 2024 |
| K L Knight Ltd | Other services | 2023 |
| K.P. Risk Services Limited | Financial services | 2010 |
| K.S Garcha & Sons Ltd | Transport & logistics | 2026 |
| K2 Innovations Ltd | Wholesale & retail | 2024 |
| K9 Motion Ltd | Other services | 2026 |
| Kane Richardson Engineering Services Limited | Manufacturing | 2003 |
| Kareers Property Solutions Ltd | Real estate | 2020 |
| Karencook Limited | Health & social care | 2016 |
| Karoshibee Ltd | Information & communication | 2020 |
| Karunya Locums Limited | Health & social care | 2012 |
| Katalina Underwriting Limited | Financial services | 2003 |
| Katana (Grantham) Ltd | Hospitality | 2017 |
| Kate Austen Limited | Professional & scientific | 2016 |
| Kate Buxton Web Design Limited | Professional & scientific | 2018 |
| Kato Wealth Planning Ltd | Professional & scientific | 2024 |
| KBR GAS Services Limited | Construction | 2013 |
| KBW Installations Limited | Construction | 2024 |
| KCM (Catering Equipment) Limited | Wholesale & retail | 2005 |
| KCS RCH LLP | | 2014 |
| Kdnd Ltd | Wholesale & retail | 2024 |
| Keane Solutions Ltd | Administrative & support | 2011 |
| Kelly Chambers Limited | Health & social care | 2025 |
| Kelly Fire Safety Solutions Ltd | Construction | 2013 |
| Kenson Property Limited | Construction | 2022 |
| Kerasia Partnership Limited | Administrative & support | 2014 |
| Kerr Build Limited | Real estate | 2024 |
| Kertech Ltd | Information & communication | 2011 |
| Kesteven and Grantham Girls' School Academy Trust | Education | 2012 |
| Kesteven Housing Limited | Real estate | 2021 |
| Kettlethorpe Sport Horses Limited | Agriculture & fishing | 2017 |
| Ketton Underwriting LLP | | 2009 |
| Keveral Underwriting LLP | | 2009 |
| Key Windows Ltd | Construction | 2025 |
| Keydee Ltd | Wholesale & retail | 2024 |
| KH Bookkeeping & Payroll Services Ltd | Professional & scientific | 2024 |
| Khan Locums Ltd | Health & social care | 2023 |
| Khaos Control Solutions EOT Ltd | Administrative & support | 2021 |
| Khaos Control Solutions Ltd | Information & communication | 2000 |
| Khaya Property Ltd | Real estate | 2019 |
| Kiaa Trade Limited | Wholesale & retail | 2025 |
| KIN Caravans Ltd | Administrative & support | 2025 |
| Kings Gardens Management Limited | Households | 2004 |
| Kingstead Investments Limited | Financial services | 2013 |
| Kirby Composting Limited | Water & waste | 2008 |
| Kirkham Precision Finance Limited | Professional & scientific | 2025 |
| Kitsune Motors Ltd | Wholesale & retail | 2024 |
| KK Global Transport Ltd | Wholesale & retail | 2021 |
| KL Garden Services Ltd | Administrative & support | 2020 |
| KLA Ltd | Health & social care | 2021 |
| Klaathex Ltd | Wholesale & retail | 2021 |
| Kleingarn Properties Ltd | Real estate | 2024 |
| Klug Group Limited | Wholesale & retail | 2020 |
| KM Mielczarek Ltd | Transport & logistics | 2014 |
| Knutsford Capital Limited | Financial services | 2017 |
| KOG Building Projects Limited | Construction | 2025 |
| Koobits Ltd | Information & communication | 2017 |
| KPL Consultancy Ltd | Professional & scientific | 2020 |
| Kpol Property Limited | Real estate | 2023 |
| KPS Motors Limited | | 1987 |
| Kreston Duncan & Toplis Limited | Professional & scientific | 2016 |
| Kriva Properties Limited | Real estate | 2023 |
| Krvy Connect Ltd | Information & communication | 2022 |
| Kssj Group Limited | Real estate | 2025 |
| Kukicandles Ltd | Other services | 2020 |
| Kukurudu Consultancy Limited | Health & social care | 2003 |
| Kula Cleaning Ltd | Administrative & support | 2022 |
| Kula Window Cleaning Ltd | Administrative & support | 2025 |
| Kuzis Limited | Wholesale & retail | 2024 |
| Kuzon Limited | Health & social care | 2025 |
| KV & Sons Ltd | Wholesale & retail | 2017 |
| KV Tuition Limited | Administrative & support | 2022 |
| KWR Plant Hire Limited | Agriculture & fishing | 2006 |
| Kyreniazith Ltd | Administrative & support | 2024 |
| L & L Property (Lincs) Limited | Real estate | 2022 |
| L Developments Ltd | Construction | 2019 |
| L M Rental Properties Limited | Real estate | 2020 |
| L R Shirtcliffe Transport Limited | Wholesale & retail | 2022 |
| L&P Bars Ltd | Hospitality | 2022 |
| L. Atkinson Limited | Administrative & support | 2012 |
| L.R.S. (Lincs) Limited | Other services | 2000 |
| L1 Nightlife Limited | Hospitality | 2025 |