| Kavalis Trans Ltd | Transport & logistics | 2019 |
| KAY and BEE Care Service Limited | Health & social care | 2025 |
| KAY Kitchens Limited | Construction | 2015 |
| KAZ Cleaning Services Limited | Administrative & support | 2024 |
| KC Home & Building Services Limited | Construction | 2023 |
| KCC (Lincs) Ltd | Transport & logistics | 2021 |
| KCC Blinds Ltd | Wholesale & retail | 2022 |
| Keal Holdings Limited | Real estate | 2016 |
| Keals Enterprise Limited | Other services | 2026 |
| Keen Clean Contracting Ltd | Administrative & support | 2024 |
| Keep IT Easy Financial Planning Ltd | Financial services | 2022 |
| Keep Surveying Ltd | Professional & scientific | 2024 |
| Keepz GK Ltd | Wholesale & retail | 2025 |
| Keith Collingwood Limited | Manufacturing | 2004 |
| Kenreth Limited | Professional & scientific | 2021 |
| Kents of Spalding Limited | Wholesale & retail | 2008 |
| Kerr Engineering Services Limited | Professional & scientific | 2026 |
| Kesh-Care Limited | Health & social care | 2008 |
| Keshwara & Sons Ltd | Wholesale & retail | 2021 |
| Keshwara Investment Limited | Financial services | 2018 |
| Kevco Consultants Limited | Administrative & support | 2016 |
| Keyan Toprak Ltd | Hospitality | 2021 |
| Keystone Properties (Boston) Ltd | Real estate | 2026 |
| Keziah Care Consult Ltd | Health & social care | 2024 |
| KGJ Ltd Limited | Transport & logistics | 2022 |
| KGJ Trans Ltd | Transport & logistics | 2023 |
| KH Freiston Ltd | Hospitality | 2026 |
| Khadija Property Ltd | Real estate | 2018 |
| Khayyam Management Services Ltd | Administrative & support | 2022 |
| Khela Consortium Limited | Real estate | 2023 |
| Khela Estates Limited | Real estate | 2015 |
| KI Trader Limited | Wholesale & retail | 2025 |
| Kidmoto Adventure Ltd | Wholesale & retail | 2025 |
| Kidsplaybostonuk Limited | Hospitality | 2025 |
| Kieran Pears Ltd | Extraterritorial | 2025 |
| Kilian Ltd | Transport & logistics | 2017 |
| Killenaule Hair Studio Ltd | Other services | 2012 |
| Kime Consultancy Limited | Information & communication | 2017 |
| King FX Ltd | Education | 2025 |
| King Wood Travel Ltd | Administrative & support | 2020 |
| Kingfisher Energy Limited | Construction | 2013 |
| Kingfisher Holdings 58 Ltd | Financial services | 2026 |
| Kings Arms Boston Ltd | Hospitality | 2021 |
| Kiosk Heaven Ltd | Wholesale & retail | 2021 |
| Kirby REN Ltd | Wholesale & retail | 2022 |
| Kirsty's Properties Limited | Real estate | 2023 |
| Kirton Caravan Storage Ltd | Transport & logistics | 2012 |
| Kirton Homes Amenity Management Limited | Households | 2004 |
| Kirton Labour Supply Limited | Administrative & support | 2005 |
| Kirton Meadows Limited | Construction | 2022 |
| Kismat Enterprise Ltd | Wholesale & retail | 2025 |
| KK Deliveries Limited | Wholesale & retail | 2015 |
| Kkns Services Ltd | Wholesale & retail | 2020 |
| Klad Creative Limited | Administrative & support | 2021 |
| Klaipeda Limited | Hospitality | 2021 |
| Klova Transport Limited | Transport & logistics | 2016 |
| KM Clean Limited | Administrative & support | 2025 |
| KM Living Ltd | Real estate | 2023 |
| KMC Plant & Tool Hire Limited | Construction | 2022 |
| KML Consulting Ltd | Professional & scientific | 2012 |
| KMS Boston Limited | Real estate | 2014 |
| Knotters Ltd | Wholesale & retail | 2026 |
| Kodioso Limited | Information & communication | 2019 |
| Kody Trans Ltd | Transport & logistics | 2022 |
| Kohba Furniture Ltd | Manufacturing | 2023 |
| Kolekto Ltd | Information & communication | 2021 |
| Komar Properties Ltd | Real estate | 2018 |
| Komissuk Ltd | Wholesale & retail | 2021 |
| Komoda Designs Ltd | Manufacturing | 2024 |
| Konfas Pallets Limited | Transport & logistics | 2015 |
| Kool Digital Ltd | Information & communication | 2026 |
| Korzinka Boston Ltd | Wholesale & retail | 2023 |
| Korzinka Limited | Wholesale & retail | 2014 |
| Korzinka Minimarket Ltd | Wholesale & retail | 2021 |
| Korzinka Taste of Europe Limited | Wholesale & retail | 2012 |
| Kostrans Ltd | Transport & logistics | 2026 |
| Koto Services Ltd | Construction | 2018 |
| Kowloon Enterprise Ltd | Hospitality | 2013 |
| KP Plumbing & Boiler Care Limited | Construction | 2014 |
| KPI Trading Limited | Wholesale & retail | 2026 |
| KPS Fresh Limited | Manufacturing | 2024 |
| KR Motor Solutions Limited | Wholesale & retail | 2021 |
| KRF Estates Ltd | Real estate | 2026 |
| Kristiana Hair Limited | Other services | 2018 |
| Kross Coaching Ltd | Arts & recreation | 2026 |
| KS Properties Limited | Real estate | 2010 |
| Ksmat Ltd | Extraterritorial | 2024 |
| KST Electrical Services Ltd | Construction | 2023 |
| Kt's Cleaning Solutions Ltd | Administrative & support | 2014 |
| KTF Tattoo Ltd | Other services | 2022 |
| KTR Consultancy Services Ltd | Administrative & support | 2019 |
| Kudos Barbers Ltd | Other services | 2024 |
| Kuveya Properties Limited | Households | 2017 |
| KW Property (Boston) Limited | Real estate | 2022 |
| KW Services (Boston) Ltd | Construction | 2021 |
| Kwik FIX Boston Ltd | Wholesale & retail | 2026 |
| Kyo-Shin Ltd | Arts & recreation | 2019 |
| Kyte Tech Inc. | | 2021 |
| L & a Fencing Supplies Ltd | Manufacturing | 2024 |
| L & a Joinery Ltd | Construction | 2021 |