| H.Coulson Building Ltd | Construction | 2025 |
| Haggitt Hill Holdings Limited | Agriculture & fishing | 2024 |
| HAH Cleaning Services Limited | Administrative & support | 2014 |
| Hambleton Automotive Limited | Real estate | 1996 |
| Hang Your HAT Property Limited | Real estate | 2024 |
| Hangover Weekends Ltd | Other services | 2017 |
| Hardwick Geophysical Ltd | Information & communication | 2021 |
| Harris Endeavor Limited | Agriculture & fishing | 2009 |
| Hatton Engineering Limited | Professional & scientific | 2007 |
| Hauxwells Building Management Company | Real estate | 1991 |
| HCL Hire Limited | Other services | 2023 |
| Hdrmed Ltd | Education | 2026 |
| Headspace Education Limited | Education | 2022 |
| Health Cluster Ltd | Wholesale & retail | 2023 |
| Hedgeside Consultancy Ltd | Administrative & support | 2017 |
| Herron Consultants Limited | Real estate | 2025 |
| Hfabrications Ltd | Manufacturing | 2026 |
| HI One Properties Limited | Real estate | 2018 |
| High Green Commercial Services Ltd | Professional & scientific | 2026 |
| Highgrove Estate Planning Limited | Financial services | 2023 |
| Highgrove Mortgage Consultants Limited | Financial services | 2016 |
| Hill House Fabrication Limited | Manufacturing | 2026 |
| Hitu Real Estate Investment Company Limited | Real estate | 2015 |
| HL Landscapes Limited | Administrative & support | 2025 |
| HL Offshore Services Ltd | Construction | 2025 |
| HMC Services Ltd | Construction | 2025 |
| Hostners Limited | Extraterritorial | 2023 |
| House of Maintenance Ltd | Construction | 2015 |
| Howie White Resourcing Limited | Administrative & support | 1999 |
| HR Alchemy Limited | Administrative & support | 2016 |
| Hugecalf Studios Ltd | Information & communication | 2016 |
| Humanwisdom Limited | Education | 2020 |
| I Lane Services Limited | Health & social care | 2023 |
| Icxinstrumentation Ltd | Construction | 2025 |
| IJ Copywriting Ltd | Professional & scientific | 2025 |
| Im-Safer Ltd | Other services | 2025 |
| Impact AV Limited | Wholesale & retail | 2020 |
| Imperial Property Development Limited | Wholesale & retail | 2015 |
| Impression Foot Clinic and Beauty Ltd | Other services | 2022 |
| IN Perpetuum Partners LLP | | 2017 |
| Inform Group Ltd | Construction | 2021 |
| Inkhaus Ltd | Other services | 2019 |
| Inspection NDT Limited | Manufacturing | 2019 |
| Interhaus Group Ltd | Real estate | 2024 |
| Isafa Limited | Financial services | 2019 |
| IT Angel Ltd | Information & communication | 2006 |
| IVY and Lily Ltd | Administrative & support | 2025 |
| IWEB365 Limited | Information & communication | 2013 |
| J and J Investments 2012 Limited | Real estate | 2013 |
| J.K.L Joinery Ltd | Manufacturing | 2023 |
| J.T.Tarran & SON Limited | Construction | 1940 |
| Jackson & Rose Homes Ltd | Real estate | 2011 |
| JAE Associates Limited | Other services | 2011 |
| Jakt Property Services Ltd | Real estate | 2023 |
| Jamroc Engineering Ltd | Mining & quarrying | 2010 |
| JB Lwood Building Ltd | Construction | 2025 |
| JB Services Ltd | Administrative & support | 2026 |
| JCN Properties Ltd | Real estate | 2026 |
| JD Bright Limited | Professional & scientific | 2014 |
| JDL Recruitment UK Limited | Administrative & support | 2020 |
| Jema Software Ltd | Information & communication | 2026 |
| Jetset Horizon Ltd | Transport & logistics | 2025 |
| JK Project Services Ltd | Professional & scientific | 2015 |
| Jkingsbury Property Investment Ltd | Real estate | 2021 |
| JMC Electrical (Yarm) Ltd | Construction | 2022 |
| Joanne K Lambert Limited | Health & social care | 2016 |
| John Muir (Saltburn) Limited | Real estate | 2005 |
| John Walker Projects Limited | Information & communication | 2016 |
| JON Carling Consultancy Limited | Professional & scientific | 2024 |
| Jopling Holdings Ltd | Real estate | 2018 |
| JR Civil Engineering Ltd | Professional & scientific | 2026 |
| JRB Protection Ltd | Administrative & support | 2023 |
| JRF Housing Ltd | Real estate | 2019 |
| JRG Crossley Limited | Administrative & support | 2017 |
| Js&Ak White Ltd | Real estate | 2018 |
| Jsavage Inspection Ltd | Professional & scientific | 2021 |
| JTJ Property Management Ltd | Real estate | 2025 |
| Jungle Pawz Ltd | Arts & recreation | 2026 |
| Just Homes Ltd | Information & communication | 2013 |
| JVR Financial Services Ltd | Financial services | 2020 |
| Jwainwrightsinging Limited | Education | 2016 |
| KD Smiles Limited | Health & social care | 2026 |
| KE4 Limited | Financial services | 2024 |
| Keaconsult Limited | Professional & scientific | 2008 |
| Keenside and Partners Ltd | Professional & scientific | 2026 |
| Kemmtag UK Ltd | Wholesale & retail | 2025 |
| Kerr Acquisitions Limited | Administrative & support | 2006 |
| Kestrel Coaching Limited | Professional & scientific | 2020 |
| Kevin Johnson Flooring Ltd | Wholesale & retail | 2011 |
| Key Stage PAY Limited | Education | 2016 |
| Key Stage Recruitment Limited | Administrative & support | 2005 |
| Keystage Energy Recruitment Limited | Administrative & support | 2026 |
| KH Liftings Limited | Professional & scientific | 2014 |
| Kirkwood Ground Care Limited | Administrative & support | 2016 |
| KKD Properties NE Limited | Real estate | 2025 |
| KLG Technical Ltd | Professional & scientific | 2025 |
| KPL Property Developments Ltd | Real estate | 2025 |
| LA Bastille Limited | Real estate | 2008 |
| LA Piazza Yarm Ltd | Hospitality | 2025 |
| Lago Homecare Limited | Health & social care | 2023 |