| IJL Coaching Ltd | Health & social care | 2021 |
| ILA Technologies Limited | Professional & scientific | 2025 |
| Ildere Limited | Real estate | 2021 |
| IM Your Transporter Ltd | Transport & logistics | 2021 |
| Imagination Commercial Holdings Limited | Professional & scientific | 1996 |
| Imagination Developments Ltd | Administrative & support | 2006 |
| Imagine Studios Limited | Arts & recreation | 2020 |
| Imajicalia Limited | Professional & scientific | 2012 |
| Indelible IP Limited | Professional & scientific | 2016 |
| Induction Technologies Ltd | Manufacturing | 2025 |
| Infant Jesus Ltd | Wholesale & retail | 2018 |
| Infinitrans Ltd | Transport & logistics | 2015 |
| Innivo Limited | Professional & scientific | 2007 |
| Innovated People Limited | Extraterritorial | 2011 |
| Intimate Limited | Wholesale & retail | 2020 |
| Intrepidbeats Limited | Information & communication | 2013 |
| IP Retail Ltd | Wholesale & retail | 2023 |
| Iron Acton Plantaria Limited | Wholesale & retail | 2019 |
| Issowed Ltd | Health & social care | 2026 |
| It-Stack Limited | Information & communication | 2002 |
| Iterate Design and Innovation Ltd | Professional & scientific | 2014 |
| Itton Development Limited | Construction | 2024 |
| J C Accounting Ltd | Professional & scientific | 2007 |
| J Hamilton Sailmakers Limited | Manufacturing | 2013 |
| J Hines Carpentry Limited | Construction | 2017 |
| J W Fisher Electrical Services Limited | Construction | 2002 |
| J&M Group Limited | Information & communication | 2002 |
| J. D. Cleverly Limited | Wholesale & retail | 1962 |
| Jacob's Welding & Fabrication Ltd | Construction | 2024 |
| JB 22 Ltd | Other services | 2024 |
| JCB Active Health Ltd | Arts & recreation | 2022 |
| JCP Property Holdings Limited | Real estate | 2024 |
| Jcrc Developments Ltd | Construction | 2024 |
| JDM Revival Ltd | Wholesale & retail | 2020 |
| Jecu Transport Ltd | Transport & logistics | 2017 |
| Jenny Shaw Consulting Ltd | Professional & scientific | 2026 |
| Jeunesse Ltd | Health & social care | 2016 |
| Jimbob & Matty's Ice Cream Limited | Hospitality | 2015 |
| JJ Construction & Design Limited | Construction | 2021 |
| JK Event Catering Ltd | Hospitality | 2022 |
| JME Premium Ltd | Construction | 2024 |
| JMH (PCA) Ltd | Other services | 2017 |
| Jmmc Media Limited | Professional & scientific | 2018 |
| JMS Companies Ltd | Arts & recreation | 2022 |
| JN Design Ltd | Information & communication | 2019 |
| Johnstone Electrical Limited | Construction | 2005 |
| Jonathan Lewis Career Services Ltd | Administrative & support | 2022 |
| Josh Purdy Mechanical Ltd | Other services | 2018 |
| JPM Services Ltd | Administrative & support | 2025 |
| JRL Creative Ltd | Information & communication | 2024 |
| Jubilee Farms Limited | Agriculture & fishing | 1977 |
| Juice Fuel Management Limited | Administrative & support | 2011 |
| Julia Zorab Limited | Professional & scientific | 1999 |
| Jurassic Resin Limited | Administrative & support | 2025 |
| Kaidex Ltd | Manufacturing | 2010 |
| KAP Commercial Ltd | Professional & scientific | 2025 |
| Karmma Properties Limited | Real estate | 2025 |
| Kartic Limited | Transport & logistics | 2018 |
| Kate's Farm LLP | | 2011 |
| KAZ Management Ltd | Other services | 2023 |
| Kealdo Ltd | Real estate | 2012 |
| Keep on Walking Limited | Professional & scientific | 2012 |
| Kelly Hammacott Mortgage & Protection Services Limited | Financial services | 2019 |
| Kenai Holdings Limited | Professional & scientific | 2013 |
| Kenai International Limited | Professional & scientific | 2023 |
| Kenai Partnership LLP | | 2013 |
| Kenai Properties Limited | Extraterritorial | 2014 |
| Kercli Limited | Hospitality | 2023 |
| Keruto KOI Ltd | Wholesale & retail | 2021 |
| Kestrel Gymnastics Ltd | Arts & recreation | 2008 |
| Keyspark Electrical Ltd | Construction | 2024 |
| KG Safeguarding & Professional Services Ltd | Public administration | 2025 |
| KH Hotel Chepstow Ltd | Hospitality | 2023 |
| Kicker Performance Consulting Limited | Professional & scientific | 2024 |
| Kiln Architects Ltd | Professional & scientific | 2020 |
| Kilo Oscar Medical & Rescue Services Ltd. | Public administration | 2024 |
| Kind Recruitment Services Ltd | Administrative & support | 2022 |
| Kind Tailored Care Ltd | Public administration | 2021 |
| Kinetic HR Solutions Ltd | Administrative & support | 2010 |
| King Street Management Company (Bristol) Limited | Real estate | 1988 |
| Kingfisher Exterior Cleaning Limited | Administrative & support | 2025 |
| Kingstone Brewery Limited | Manufacturing | 2015 |
| Kinross Developments Limited | Real estate | 2004 |
| Kismet Engineering Limited | Professional & scientific | 2019 |
| Kite Training & Education Ltd | Extraterritorial | 2021 |
| KJB Security Ltd | Administrative & support | 2025 |
| Kjdit Limited | Information & communication | 2019 |
| Knightwood Development Group Ltd | Construction | 2026 |
| Knjdevelopments Limited | Construction | 2024 |
| Koan (UK) Ltd | Wholesale & retail | 2004 |
| Koda Holdings Ltd | Financial services | 2021 |
| Koeko Ltd | Professional & scientific | 2014 |
| Koxy & Co Ltd | Wholesale & retail | 2025 |
| KSW Art Ltd | Arts & recreation | 2023 |
| Kudos Companies Limited | Manufacturing | 2010 |
| KVR Enterprises Limited | Wholesale & retail | 2025 |
| L a Project Services Limited | Professional & scientific | 1985 |
| L B Mitchell Ltd | Construction | 2026 |
| LAM888 Holdings Limited | Financial services | 2023 |
| Landpoint Construction Ltd | Construction | 2018 |