| J.H. Hutchinson & SON Limited | Agriculture & fishing | 2006 |
| J.J. Harrison Landscapes Ltd | Administrative & support | 2002 |
| J.J.S. Trading Limited | Wholesale & retail | 1982 |
| J.M. Bollands Joinery Limited | Manufacturing | 2002 |
| J.R.C Elecrtical - Whitby Ltd | Manufacturing | 2025 |
| JAB Engineering Limited | Professional & scientific | 2007 |
| Jabell Limited | Wholesale & retail | 2022 |
| Jackanory Limited | Extraterritorial | 2006 |
| JAK Landscaping Limited | Administrative & support | 2018 |
| Jake Ross Consulting Ltd | Professional & scientific | 2026 |
| Java of Whitby Ltd | Hospitality | 2006 |
| JB Trading Group Ltd | Wholesale & retail | 2022 |
| JC Shrine Property Ltd | Real estate | 2020 |
| JCF Marine Limited | Manufacturing | 2020 |
| Jefferson Building Limited | Construction | 2009 |
| Jessica Hogarth Ltd | Arts & recreation | 2022 |
| JET Black Jewel Limited | Hospitality | 2020 |
| JET Black of Whitby Ltd | Wholesale & retail | 2014 |
| JGD Solutions Ltd | Financial services | 2022 |
| John Broadwood and Sons Limited | Manufacturing | 2008 |
| John Corner Funeral Service Limited | Other services | 2012 |
| John Lees (Aerials) Ltd | Administrative & support | 2002 |
| John Lloyd Ltd | Construction | 2023 |
| John Noble Ltd | Construction | 2001 |
| Jollie Hollies Company Ltd | Real estate | 2010 |
| Joly Holdings Ltd | Real estate | 2024 |
| Journey-Blue Limited | Wholesale & retail | 2020 |
| JPD Hospitality Ltd | Hospitality | 2025 |
| JPL Drawing Services Limited | Professional & scientific | 2006 |
| JSC Scaffolding Compliance Limited | Construction | 2026 |
| JTP Plumbing and Heating Ltd | Construction | 2020 |
| Justasoap Limited | Manufacturing | 2021 |
| Justin Waring Properties Limited | Hospitality | 2017 |
| Justins Confectionery Limited | Manufacturing | 2013 |
| Jwae Limited | Mining & quarrying | 2013 |
| JWC Racing Ltd | Other services | 2024 |
| K & D Building & Property Renovations Limited | Construction | 2020 |
| K & N Property Ltd | Real estate | 2021 |
| K & S Dryden Limited | Hospitality | 2023 |
| K Greenwood Limited | Professional & scientific | 2019 |
| K T and J Hospitality Limited | Hospitality | 2024 |
| K.R. Bedlington Ltd | Other services | 2003 |
| K.W. Harrison (Whitby) Limited | Construction | 2001 |
| Kaks Engineering Ltd | Construction | 2026 |
| Kamber Ltd | Education | 2024 |
| Kamthai Restaurant Limited | Hospitality | 2019 |
| KCCRAWLEY83 Limited | Energy | 2018 |
| Kcme Limited | Extraterritorial | 2012 |
| Keel Cottage Ltd | Hospitality | 2018 |
| Keeper Homes Ltd | Construction | 2023 |
| Keepers Court (Block 3) Whitby Ltd | Real estate | 2021 |
| Keepers Court Whitby 1-6 Limited | Households | 2021 |
| Keepers Court Whitby 7-12 Limited | Real estate | 2021 |
| Keith H Attridge Ltd | Construction | 2014 |
| Kellakier Limited | Transport & logistics | 2021 |
| Kemp Productions Ltd | Administrative & support | 2026 |
| Kildale Show Limited | Arts & recreation | 2012 |
| Kingfisher Freehold Limited | Households | 2020 |
| Kirbys (Whitby) Limited | Households | 1979 |
| Kirkham Estate Holdings Ltd | Financial services | 2019 |
| Kirkham Manufacturing Ltd | Manufacturing | 2018 |
| Kirkham Wholesale Ltd | Wholesale & retail | 2019 |
| Kjkm & Sons Limited | Real estate | 2013 |
| Klondike Music UK Ltd | Information & communication | 2020 |
| KMB Health Care Ltd | Extraterritorial | 2024 |
| Knight Coffee Shop Limited | Hospitality | 2019 |
| Knight Hospitality Ltd | Hospitality | 2025 |
| Knight's Retreat (Whitby) Ltd | Real estate | 2022 |
| Kristy's Limited | Other services | 2018 |
| Kssh Management Ltd | Hospitality | 2024 |
| Kyber Barr Limited | Hospitality | 2017 |
| L & M (Whitby) Limited | Extraterritorial | 2012 |
| L D S Developments Limited | Construction | 2005 |
| L&L Hospitality Limited | Hospitality | 2023 |
| L.M. Minerals Ltd | Financial services | 2013 |
| Lady Luck Brewery Limited | Manufacturing | 2019 |
| Lagopus Property Ltd | Real estate | 2025 |
| Lanetech Ltd | Professional & scientific | 2023 |
| Lawrence & Cross Ltd | Hospitality | 2014 |
| Lawson Builders and High Access Limited | Construction | 2011 |
| Lawson Consultancy U.K. Ltd | Professional & scientific | 2016 |
| Layla Rhode Limited | Wholesale & retail | 2023 |
| Layout Concepts Ltd | Manufacturing | 2026 |
| LBO Fisheries Ltd | Agriculture & fishing | 2025 |
| Leaf Commercial Limited | Real estate | 2024 |
| Leaf HMO Limited | Real estate | 2024 |
| Leaf Holdings Investments Limited | Financial services | 2024 |
| Leaf Property Investments Limited | Real estate | 2024 |
| Lealex Limited | Wholesale & retail | 2012 |
| Lealholm Auto Services Ltd | Wholesale & retail | 2016 |
| Lealholm Community & Sports CIC | Arts & recreation | 2025 |
| Lealholm Community Support | Other services | 2018 |
| Leesholme Management Company Limited | Households | 2016 |
| Lest WE Forget Ltd | Extraterritorial | 2020 |
| Letstern Limited | Information & communication | 2025 |
| Lgrl Limited | Administrative & support | 2012 |
| Liberty Prize Draw Ltd | Other services | 2025 |
| Lighthouse Bay Ltd | Wholesale & retail | 2022 |
| Lighthouse N.E Ltd | Hospitality | 2021 |
| Lighthouse Wills and Estate Limited | Professional & scientific | 2024 |