| Hawthorn Tree Community Children's Centre | Education | 2014 |
| Hayward Farms Limited | Administrative & support | 2009 |
| HB House Limited | Hospitality | 2021 |
| HD Financial Advice Limited | Financial services | 2017 |
| HD Wills and Estate Planning Ltd | Professional & scientific | 2022 |
| HDM Construction Ltd | Construction | 2016 |
| Head Start Ramsey Nursery Limited | Health & social care | 2015 |
| Headlines (Swineshead) Limited | Other services | 2015 |
| Headway Lincolnshire | Other services | 2012 |
| Healthy Homecare Property Holdings Ltd | Real estate | 2020 |
| Healthy Homecare Services Ltd | Health & social care | 2012 |
| HEAR4LINCS CIC | Education | 2025 |
| Heatport Ltd | Wholesale & retail | 2020 |
| Heavygo Ltd | Transport & logistics | 2026 |
| Heckington and District Agricultural Society | Other services | 2004 |
| Heissen Ltd | Wholesale & retail | 2019 |
| Hektor Pro Ltd | Construction | 2015 |
| Hellen Nwhealthcare Services UK Ltd | Health & social care | 2022 |
| Hempstead Screen Repair Ltd | Wholesale & retail | 2026 |
| Henmil Limited | Real estate | 2013 |
| Henry Tunnard Limited | Agriculture & fishing | 1956 |
| Herc Services Ltd | Administrative & support | 2019 |
| Hereditas Generum Ltd | Professional & scientific | 2025 |
| Hessa Food and Drinks Ltd | Wholesale & retail | 2025 |
| HF Dentl Health Ltd | Health & social care | 2026 |
| HGM Estate Ltd | Real estate | 2026 |
| HGV - Sungsuvan Ltd | Transport & logistics | 2025 |
| HHC Trading Company Ltd | Wholesale & retail | 2011 |
| Hhwnts Limited | Hospitality | 2020 |
| HI Street Shop Ltd | Wholesale & retail | 2025 |
| Highgate Day Nursery Limited | Health & social care | 2015 |
| Hilary Sean Services Limited | Professional & scientific | 2014 |
| Hill Top Hens Ltd | Agriculture & fishing | 2025 |
| Hilltech Engineering UK Ltd. | Manufacturing | 2019 |
| Histed Engineering Ltd | Extraterritorial | 2023 |
| HJE Property Solutions Ltd | Real estate | 2025 |
| HJL Builders Limited | Construction | 2024 |
| HLS Security Ltd | Administrative & support | 2023 |
| HMJ Distributions Ltd | Wholesale & retail | 2026 |
| Hobhole Farming Limited | Agriculture & fishing | 2010 |
| Hobhole Properties Limited | Real estate | 2002 |
| Hogg Ricweld Limited | Manufacturing | 2014 |
| Holistic Care Clinic Ltd | Health & social care | 2025 |
| Holloway Marketing Limited | Real estate | 2025 |
| Holme Farm Group Holdings Limited | Manufacturing | 1999 |
| Holmewood Arable Ltd | Agriculture & fishing | 2011 |
| Home Works (Boston) Ltd | Wholesale & retail | 2012 |
| Home YOU Like (Boston) Ltd | Hospitality | 2016 |
| Home YOU Like Limited | Households | 2015 |
| Homes 4 Rent Limited | Real estate | 2007 |
| Homestead Property Lets Limited | Hospitality | 2014 |
| Hope Street Management Limited | Hospitality | 2007 |
| Hopgood Consulting Ltd | Information & communication | 2019 |
| Horacek Trans Ltd | Transport & logistics | 2019 |
| Horizon Force Ltd | Professional & scientific | 2022 |
| Hornbeam Property Limited | Real estate | 2018 |
| Horseshoe Close Limited | Real estate | 2006 |
| Horstead & Hill Limited | Real estate | 2020 |
| Hortus Green Limited | Energy | 2018 |
| Hostie Ltd | Manufacturing | 2022 |
| Hotels Direct Ltd | Hospitality | 2022 |
| Houghton Mifflin Company International, Inc. | | 1992 |
| Hovels Limited | Real estate | 2017 |
| HQ Built Ltd | Other services | 2024 |
| HRG Homes Limited | Construction | 2021 |
| HS and Team Limited | Health & social care | 2024 |
| HS Group of Companies Ltd | Financial services | 2021 |
| HS Health Group Limited | Health & social care | 2011 |
| HS Hospitality and Leisure Limited | Arts & recreation | 2024 |
| HS Realty and Properties Ltd | Real estate | 2022 |
| HT Nails 39 Ltd | Other services | 2023 |
| HTG Accountants Limited | Professional & scientific | 2023 |
| Htnp Limited | Real estate | 2023 |
| Humanity Health | | 2019 |
| Hundred Acre Farm Ltd | Agriculture & fishing | 2023 |
| Hungry Pike Ltd | Wholesale & retail | 2018 |
| Hwlincs | Information & communication | 2012 |
| Hydro Force Ltd | Administrative & support | 2026 |
| Hyusein Selman Car Wash Limited | Wholesale & retail | 2024 |
| I & J Tyler Ltd | Information & communication | 2023 |
| I and J Tyler (Holdings) Ltd | Financial services | 2024 |
| I and J Tyler (Property) Ltd | Hospitality | 2024 |
| I and T Housing Ltd | Real estate | 2025 |
| I Develop Lighting Ltd | Manufacturing | 2023 |
| I J Cobby Limited | Administrative & support | 2002 |
| I S Boston Ltd | Real estate | 2025 |
| I&M Cleaning Services Ltd | Administrative & support | 2025 |
| I. O. E. Limited | Health & social care | 2003 |
| I.N.T. Driving School Ltd | Education | 2013 |
| I.P.J. Services Limited | Wholesale & retail | 2002 |
| IAN Grant Farms | Financial services | 2024 |
| IAN Grant Leisure & Marine Limited | Transport & logistics | 1990 |
| Ibag Trading Ltd | Wholesale & retail | 2022 |
| Ibus Services UK Ltd | Construction | 2024 |
| ICA Improvements Ltd | Construction | 2020 |
| Ican Interiors Ltd | Manufacturing | 2024 |
| ID Electrics Ltd | Administrative & support | 2026 |
| ID Solutions Ltd | Administrative & support | 2026 |
| ID2 Studio Ltd | Administrative & support | 2007 |
| IDB Site Services Ltd | Construction | 2025 |