| Julius Petraitis Limited | Construction | 2014 |
| Juma Medical Group Ltd | Health & social care | 2025 |
| Jumpstart IT Systems Limited | Information & communication | 2019 |
| JUN YAN Ltd | Hospitality | 2025 |
| Junyang Industrial Co., Limited | Administrative & support | 2023 |
| Jurassic Perk Ltd | Other services | 2016 |
| Just Accountants (UK) Limited | Information & communication | 2019 |
| Just-Accountants Limited | Professional & scientific | 2013 |
| JUST4SPORTS Ltd | Education | 2023 |
| JUT Cleaning Services Limited | Other services | 2023 |
| JW Home Improvements Limited | Construction | 2018 |
| JXB Group Ltd | Wholesale & retail | 2023 |
| Jyye Limited | Administrative & support | 2022 |
| K Global Services Ltd | Construction | 2017 |
| K I Logistics Ltd | Transport & logistics | 2021 |
| K O'Donoghue & Sons Limited | Construction | 2025 |
| K O'Donoghue Ltd | Construction | 2011 |
| K O'Donoghue Painting & Decorating Limited | Construction | 2022 |
| K Specialist Cars Ltd | Wholesale & retail | 2025 |
| K Twins Limited | Real estate | 2019 |
| K&B Haulage & Plant Hire Ltd | Transport & logistics | 2023 |
| K&G Group Bournemouth Ltd | Real estate | 2024 |
| K&S Inspired Innovation Ltd | Wholesale & retail | 2025 |
| K.Eule Ltd | Professional & scientific | 2019 |
| K3 Property Management Ltd | Real estate | 2011 |
| K9 Capers Limited | Other services | 2005 |
| KA Byrne Vehicle Body Repair Ltd | Wholesale & retail | 2022 |
| KAA Trading Limited | Hospitality | 2017 |
| Kaara Ltd | Wholesale & retail | 2025 |
| Kabuki's Bakes Ltd | Manufacturing | 2026 |
| Kaderbhai Products Ltd | Wholesale & retail | 2025 |
| KAL Residential Limited | Real estate | 2021 |
| Kalimaa Ltd | Real estate | 2025 |
| Kallides&Sons Ltd | Construction | 2025 |
| Kalpanand IT Solutions Limited | Information & communication | 2014 |
| Kalvin Capital Ltd | Financial services | 2025 |
| Kalvin Investments Ltd | Real estate | 2016 |
| Kalvinsec Ltd | Information & communication | 2025 |
| Kamawi Constructions Limited | Construction | 2023 |
| Kamila Property Investment Limited | Real estate | 2007 |
| Kamsol Limited | Administrative & support | 2012 |
| KAN Properties Ltd | Real estate | 2010 |
| Kana Direct Ltd | Wholesale & retail | 2020 |
| Kanak Lata Properties Limited | Administrative & support | 2007 |
| Kann Limited | Real estate | 2017 |
| Kanta Investments Limited | Real estate | 2025 |
| Kanyam Limited | Real estate | 2020 |
| Kapi Properties Ltd | Real estate | 2026 |
| Kapoor and Sons Enterprises Limited | Wholesale & retail | 2017 |
| Kappa Properties Ltd | Real estate | 2022 |
| Karam Hekmat Ltd | Administrative & support | 2025 |
| Karenza Properties Ltd | Real estate | 2024 |
| Karmak Ltd | Wholesale & retail | 2022 |
| Karter Capital LLP | | 2018 |
| Karter Investments Ltd | Real estate | 2016 |
| Kartoos Ltd | Wholesale & retail | 2020 |
| Kasiyan Limited | Information & communication | 2021 |
| Kassam Limited | Other services | 2012 |
| Kate's Waffle Cabin Ltd | Hospitality | 2023 |
| Kateb Interiors Ltd | Wholesale & retail | 2025 |
| Kazakov Properties Ltd | Real estate | 2025 |
| KB Management Services Ltd | Information & communication | 2007 |
| KBR Executive Travel Ltd | Transport & logistics | 2025 |
| KCH Tech Limited | Wholesale & retail | 2019 |
| Keane Carpentry Ltd | Information & communication | 2022 |
| Keaney Construction Limited | Construction | 2018 |
| Keany Limited | Real estate | 2021 |
| Kearns (Boston Manor) Ltd | Real estate | 2019 |
| Kearns (Chippendale Way) Ltd | Real estate | 2019 |
| Kearns Development Ltd | Construction | 2016 |
| Kearns Enterprises Limited | Real estate | 2021 |
| Kearns Group Holdings Limited | Financial services | 2024 |
| Kearns Property Ltd | Real estate | 2019 |
| Kearns Residential Ltd | Real estate | 2019 |
| Kedavo Integrated Services Limited | Health & social care | 2023 |
| Keep Calm and Carry on Saving Ltd | Wholesale & retail | 2017 |
| Keep Powder Coating Ltd | Construction | 2025 |
| Keepsite Industries LLP | | 2012 |
| Keepy Uppy Limited | Administrative & support | 2002 |
| Keiman Properties Ltd | Real estate | 2020 |
| Keiman Technologies Ltd | Information & communication | 2025 |
| Keizen SDK Ltd | Manufacturing | 2012 |
| Kelensi Consulting Ltd | Professional & scientific | 2026 |
| Kelly Cornish Properties Ltd | Real estate | 2020 |
| Keltics Arkadia Limited | Wholesale & retail | 2005 |
| Kendalls News Ltd | Wholesale & retail | 2018 |
| Keneeto Clothing Limited | Wholesale & retail | 2023 |
| Kenmark Tech Solutions Management UK Ltd | Professional & scientific | 2016 |
| Kenna Education Group Ltd | Education | 2026 |
| Kensington Painting & Decorating Services Limited | Construction | 2011 |
| Kentish Roofing & Building Limited | Construction | 2022 |
| Kenzi Interior Designs. Ltd | Wholesale & retail | 2021 |
| Keshun Imp&Exp Co., Ltd | Administrative & support | 2022 |
| Keshwi Patel Limited | Health & social care | 2024 |
| Kestwill Associates Limited | Professional & scientific | 2019 |
| Kestwill Collectibles Limited | Wholesale & retail | 2020 |
| Ketina Services Ltd | Hospitality | 2025 |
| Kevin&Son Ltd | Transport & logistics | 2016 |
| Kevnita Enterprises Ltd | Administrative & support | 2023 |
| Keycraft Paving & Patios Limited | Administrative & support | 2023 |