| I-Appoint Ltd | Professional & scientific | 2004 |
| IBT Power Limited | Professional & scientific | 2001 |
| Ilminster Greetings Ltd | Wholesale & retail | 2013 |
| Imaginary Friends Productions Limited | Information & communication | 2010 |
| Impact Stunts Limited | Arts & recreation | 2005 |
| Impala Software Limited | Professional & scientific | 1995 |
| Implicit Limited | Information & communication | 2016 |
| Importsbiz Limited Liability Partnership | | 2008 |
| IN Gallery Ltd | Arts & recreation | 2022 |
| IN Stitches by Julie Black Ltd | Manufacturing | 2024 |
| Independent Surveyors and Valuers Association | Professional & scientific | 1995 |
| Independent Surveyors Association | Extraterritorial | 2010 |
| Independent Surveyors Network Limited | Extraterritorial | 1995 |
| Independent Surveyors Training | Education | 2000 |
| Indira Limited | Hospitality | 1996 |
| Integen Services Ltd | Professional & scientific | 2020 |
| Integra Blue Web Agency Limited | Information & communication | 2014 |
| Into Digital Ltd | Administrative & support | 2019 |
| IQS Claims Consultancy Ltd | Professional & scientific | 2006 |
| Isotope Management Systems Ltd | Professional & scientific | 2024 |
| IVY Group Investments Limited | Hospitality | 2022 |
| J a Stewart Tree Surgery Ltd | Agriculture & fishing | 2023 |
| J C Plumbing & Heating (Dorset) Ltd | Construction | 2023 |
| J Dixon Post Production Limited | Information & communication | 2015 |
| J Green Limited | Professional & scientific | 2013 |
| J. J. Nowell Ltd | Real estate | 2019 |
| Jack Mcpartland Ltd | Information & communication | 2012 |
| Jaimes Barber Surveys Ltd | Construction | 2024 |
| Jake Birkett Computer Solutions Limited | Information & communication | 2002 |
| James Brown Electrical Ltd | Construction | 2023 |
| James Brown Property Ltd | Real estate | 2019 |
| James Burt Design Ltd | Construction | 2016 |
| Jandust Business Sage Ltd | Administrative & support | 2023 |
| JDR Legal Services Limited | Professional & scientific | 2024 |
| Jeune Holdings Ltd | Financial services | 2018 |
| Jeune Property Ltd | Real estate | 2017 |
| JGJ Properties Limited | Real estate | 2023 |
| Jhai Limited | Construction | 2000 |
| JL Electrical (Dorset) Limited | Construction | 2013 |
| JM Internet Ltd | Information & communication | 2005 |
| JME Melplash LP | | 2021 |
| JO Richardson Ltd | Health & social care | 2016 |
| JOE Muhl Co Ltd | Administrative & support | 2020 |
| John Blanchard HSE UK Limited | Professional & scientific | 2015 |
| John Keil Investments Limited | Real estate | 1962 |
| John Keil Limited | Real estate | 1958 |
| John Williams (Charmouth) Limited | Construction | 2003 |
| Joseph James Limited | Professional & scientific | 2004 |
| JRF Accountancy Solutions Limited | Professional & scientific | 2015 |
| Jsbeverage Limited | Hospitality | 2025 |
| JSR Scaffolding Ltd | Construction | 2021 |
| JSS (Dorchester) Limited | Real estate | 2000 |
| JSW Entertainment Group Limited | Arts & recreation | 2022 |
| Jthink Limited | Information & communication | 2004 |
| Jtme Ltd | Information & communication | 2014 |
| Jurassic Coast Healthcare Limited | Health & social care | 2015 |
| Jurassic Coast Holiday Homes Ltd | Hospitality | 2022 |
| Jurassic Coast Property Management Limited | Hospitality | 2020 |
| Jurassic Kites Ltd | Wholesale & retail | 2015 |
| Jurassic Pond Solutions Limited | Administrative & support | 2023 |
| Jurassic PUB Co Ltd | Hospitality | 2023 |
| Just BE Jerkin Ltd | Hospitality | 2026 |
| Just Before IT Happened Ltd | Arts & recreation | 2019 |
| Just Fish Limited | Hospitality | 2023 |
| Just Pedal Limited | Administrative & support | 2012 |
| Justice League C.I.C. | Information & communication | 2021 |
| KA Brown Consulting Limited | Professional & scientific | 2016 |
| Karapinar Energy Ltd | Mining & quarrying | 2020 |
| Karen Beach RPA Services Ltd | Professional & scientific | 2023 |
| Karis Limited | Information & communication | 1999 |
| Katex Limited | Wholesale & retail | 2011 |
| Keil Holdings Limited | Professional & scientific | 1961 |
| KEM Media Ltd | Professional & scientific | 2018 |
| Kidmore Close Residents Association Limited | Households | 1983 |
| Kids 1 Trust | Extraterritorial | 2010 |
| Kingsland Farm Limited | Construction | 2010 |
| Kites for Schools Limited | Manufacturing | 2008 |
| Kitson & Trotman (Legal Services) Limited | Extraterritorial | 2013 |
| Kitson & Trotman LLP | | 2013 |
| Kitson & Trotman Trust Corporation Limited | Other services | 2025 |
| Knapp Estate Management Limited | Real estate | 1997 |
| Knights Ventures Ltd | Information & communication | 2020 |
| Kura Haus Ltd | Other services | 2026 |
| KVP (EU) Limited | Wholesale & retail | 2014 |
| KW Structures Limited | Professional & scientific | 2013 |
| Lamberts Castle Shooting Club Limited | Arts & recreation | 2026 |
| Lancombes House Technical Services Limited | Wholesale & retail | 2008 |
| Landforms Studio CIC | Professional & scientific | 2025 |
| Lansdowne Property Services Limited | Administrative & support | 2016 |
| LAP Locum Ltd | Health & social care | 2023 |
| Lasting Impressions (Signs) Ltd | Manufacturing | 2005 |
| Laurence Norman Hospitality Ltd | Wholesale & retail | 2018 |
| Layla 07 Ltd | Hospitality | 2025 |
| Lbrc Ltd | Transport & logistics | 2014 |
| Leakers Limited | Manufacturing | 2002 |
| Leandos Pizzas Ltd | Hospitality | 2019 |
| LEE Incorporated Ltd | Administrative & support | 2025 |
| Left EYE TV Ltd | Information & communication | 2015 |
| Lensomy Lifestyle Ltd | Wholesale & retail | 2023 |
| Let's GET Running Ltd | Arts & recreation | 2011 |