| John Rolfe Financial Services Limited | Financial services | 2014 |
| John Stiles Ltd | Construction | 2015 |
| John Tite Car Repairs Ltd | Wholesale & retail | 2016 |
| Joint Surgery Expert Limited | Real estate | 2021 |
| Jolliffe Builders Limited | Real estate | 2006 |
| Jolliffe Developers Holdings Limited | Real estate | 2016 |
| JON Hodges Industrial Design Limited | Professional & scientific | 2021 |
| JON Shiner Limited | Information & communication | 2010 |
| Jonrah Management Limited | Professional & scientific | 2021 |
| Josephine Charters Limited | Administrative & support | 2015 |
| Joto Enterprises Limited | Real estate | 2001 |
| Jove Properties (2) Limited | Professional & scientific | 2005 |
| Joy Lane & Co Ltd | Professional & scientific | 2018 |
| Joy Total Health Care Services Ltd | Health & social care | 2023 |
| Joyla Limited | Wholesale & retail | 2023 |
| Jpcp Electrical Ltd | Construction | 2023 |
| JPS Dorset Ltd | Wholesale & retail | 2015 |
| JR Newco Limited | Administrative & support | 2010 |
| JS Irwin Security Services Ltd | Administrative & support | 2021 |
| JSC Contractors Limited | Agriculture & fishing | 2006 |
| JSK Groundworks Ltd | Construction | 2018 |
| JT Contracting Ltd | Wholesale & retail | 2024 |
| JTM Landscapes Limited | Construction | 2013 |
| Jubilee Court (Dorchester) Residents Management Company Limited | Hospitality | 1980 |
| Judder Limited | Information & communication | 2018 |
| Julie Montagu Limited | Administrative & support | 2012 |
| Julie Montagu School of Yoga Limited | Other services | 2017 |
| Julien Watkins Pipework Services Ltd | Construction | 2021 |
| Jupiter Films Ltd | Information & communication | 2015 |
| Jurassic Bees Limited | Agriculture & fishing | 2019 |
| Jurassic Coachworks Ltd | Wholesale & retail | 2025 |
| Jurassic Coast Collective Ltd | Hospitality | 2026 |
| Jurassic Coast Farm Shop Ltd | Wholesale & retail | 2018 |
| Jurassic Coast Fine Foods Ltd | Agriculture & fishing | 2008 |
| Jurassic Coast Landscaping Ltd | Administrative & support | 2022 |
| Jurassic Coast Trading Ltd | Manufacturing | 2019 |
| Jurassic Doors Ltd | Construction | 2021 |
| Jurassic Driveways Ltd | Administrative & support | 2019 |
| Jurassic Embroidery Ltd | Wholesale & retail | 2022 |
| Jurassic Forex & Commodities Ltd | Professional & scientific | 2024 |
| Jurassic Huts Ltd | Manufacturing | 2021 |
| Jurassic Hydroponics Ltd | Professional & scientific | 2026 |
| Jurassic Muscle Limited | Arts & recreation | 2020 |
| Jurassic Property Ltd | Real estate | 2018 |
| Jurassic Reclamation Ltd | Wholesale & retail | 2018 |
| Jurassic Scaffolding Limited | Construction | 2025 |
| Just Enterprise UK Limited | Health & social care | 2008 |
| Just Grillin' Ltd. | Hospitality | 2019 |
| Just Properties (Buckingham) Limited | Administrative & support | 1970 |
| Justin Brooker Ltd | Construction | 2006 |
| JW Flat Roofing Solutions Ltd | Construction | 2025 |
| Jwhitehead Consultancy Ltd | Professional & scientific | 2024 |
| JWS Services Dorset Ltd | Professional & scientific | 2023 |
| JYA Estate Planning Ltd | Professional & scientific | 2024 |
| K & M Decorating Limited | Construction | 2009 |
| K a AXE Limited | Hospitality | 2023 |
| K Hunter Retail Limited | Wholesale & retail | 2013 |
| K M Buckland Agricultural Contractor Limited | Agriculture & fishing | 2004 |
| K M Skip Hire Limited | Water & waste | 2002 |
| K Tamlin Limited | Hospitality | 2016 |
| K.A.M. Farming Limited | Agriculture & fishing | 1992 |
| K.Chester Business Services Ltd | Administrative & support | 2026 |
| Kafe Fontana Dorset Limited | Hospitality | 2020 |
| Kandahar Palace Limited | Arts & recreation | 2025 |
| Kandahar SKI Club Limited | Arts & recreation | 1989 |
| Kanji Global Ltd | Professional & scientific | 2023 |
| KAO SAN Limited | Hospitality | 2016 |
| KAP Woodwork & Building Services Ltd | Manufacturing | 2024 |
| Karim JR Limited | Health & social care | 2018 |
| Kazumi Leeds Ltd | Hospitality | 2021 |
| Kazumi Wilmslow Road Limited | Hospitality | 2021 |
| KB Building & Plastering SW Ltd | Construction | 2024 |
| KCO Studios Limited | Professional & scientific | 2022 |
| Keast Court Management Company Limited | Households | 1989 |
| Keiran Burke Racing Ltd | Arts & recreation | 2023 |
| Kemnal Limited | Real estate | 1959 |
| Kemp & Co Property Ltd | Real estate | 2012 |
| Kensington Clothes Limited | Wholesale & retail | 2025 |
| Kensington Pickleball Club Ltd | Arts & recreation | 2023 |
| Kensington Pickleball LLP | | 2025 |
| Kent Enterprises (Bournemouth) Limited | Other services | 2016 |
| Kerala Food Corner Ltd | Hospitality | 2025 |
| Kevin Joy Ltd | Administrative & support | 2017 |
| Kevin Morris Heritage Planning Limited | Professional & scientific | 2017 |
| Kevin Smith Carpentry Ltd | Construction | 2019 |
| Key Digital Agency Limited | Information & communication | 2007 |
| Key Marine and Aviation Finance LLP | | 2009 |
| Kiaora Plumbing & Heating Limited | Energy | 2009 |
| Kiba Insights Ltd | Information & communication | 2011 |
| Kickstart Vitality Ltd | Education | 2025 |
| Kiing Blue Eyes Ltd | Other services | 2019 |
| Kindsworth Care LP | | 2022 |
| King Build and Maintenance Limited | Construction | 2019 |
| Kingdom Place Limited | Administrative & support | 2013 |
| Kings Waste Solutions Limited | Manufacturing | 2007 |
| Kingsbury Court (Weymouth) Management Limited | Real estate | 2004 |
| Kingsbury Weymouth Unlimited | Real estate | 2003 |
| Kingscote Management Company Dorchester (2004) Limited | Real estate | 2004 |
| Kingsley (Southern) Limited | Administrative & support | 2015 |
| Kingston Maurward Studio School Limited | Education | 2012 |