| Ieyya Ltd | Wholesale & retail | 2025 |
| Iffat Property Invesment Ltd | Real estate | 2024 |
| IFL Trans Ltd | Transport & logistics | 2018 |
| Ignite Education and Consultancy Service Limited | Education | 2017 |
| Ignite Plumbing and Heating Northants Ltd | Construction | 2018 |
| Ikhwah Ltd | Wholesale & retail | 2025 |
| Ily’S Hair Studio Ltd | Other services | 2021 |
| Image Ceramics Limited | Administrative & support | 1999 |
| Imagine Computing Solutions Limited | Information & communication | 2007 |
| Imago Unica Ltd | Health & social care | 2026 |
| Imberg Consultancy Ltd | Information & communication | 2010 |
| Imhim Limited | Information & communication | 2026 |
| Immunisations UK Ltd | Health & social care | 2021 |
| Imole Cosmetics Ltd | Wholesale & retail | 2025 |
| IMP Driving Services Ltd | Transport & logistics | 2016 |
| IMP Utilities Ltd | Construction | 2019 |
| Impact Solutions Group Ltd | Information & communication | 2022 |
| Impeccable Cleaners Ltd | Administrative & support | 2024 |
| Imperium Training and Asset Management Limited | Administrative & support | 2015 |
| Imprinted Ltd | Wholesale & retail | 2020 |
| IN Bloom (Rushden) Limited | Wholesale & retail | 2022 |
| IN Camera Accounting Limited | Professional & scientific | 2021 |
| IN Vitro Technology Limited | Professional & scientific | 2016 |
| In-Build Property Services Ltd | Construction | 2024 |
| IN4 Logix Ltd | Wholesale & retail | 2024 |
| Incarnie Limited | Wholesale & retail | 2022 |
| Incoming Group Ltd | Information & communication | 2026 |
| Indale Ltd | Manufacturing | 2017 |
| India Restaurant ( Sudbury) Ltd. | Hospitality | 2013 |
| Indian Chef Northants Ltd | Hospitality | 2018 |
| Indian Curry House Ltd | Hospitality | 2026 |
| Indian Food Takeaway Ltd | Hospitality | 2023 |
| Indian Takeaway Bozeat Ltd | Hospitality | 2023 |
| Indianaromaflavours Limited | Hospitality | 2026 |
| Indus Impressionz Ltd | Wholesale & retail | 2025 |
| Industrial Control Distributors Limited | Manufacturing | 1998 |
| Industrial Roofing South Ltd | Construction | 2017 |
| Industrial Services (Telford) Limited | Arts & recreation | 1960 |
| Indy House Renovation Ltd | Construction | 2020 |
| Infinite Luxe Events Ltd | Other services | 2025 |
| Inga Transport Ltd | Transport & logistics | 2017 |
| Ingallsayles Limited | Professional & scientific | 2007 |
| Inicio Property Group Ltd | Real estate | 2022 |
| INK Bucket Limited | Wholesale & retail | 2013 |
| Inkjet Control Systems Limited | Manufacturing | 2006 |
| Inmarble Ltd | Construction | 2020 |
| Inn These Shoes Ltd | Hospitality | 2023 |
| Inseal Creative Ltd | Professional & scientific | 2025 |
| Insituform Linings Limited | Manufacturing | 1983 |
| Inspire Windscreens Ltd | Wholesale & retail | 2024 |
| Inspired Beauty Ltd | Other services | 2016 |
| Insta Power Electrical Contractors Ltd | Construction | 2025 |
| Insta Power Ltd | Construction | 2025 |
| Instant Tax Advice Limited | Professional & scientific | 1997 |
| Instinct Courier Services Ltd | Transport & logistics | 2019 |
| Instinct Staffing Ltd | Health & social care | 2017 |
| Instinctive Performance Limited | Manufacturing | 2026 |
| Inte-Gen Ltd | Manufacturing | 2011 |
| INTEGR8ARCHERY CIC | Education | 2022 |
| Integrity Consultancy & Services Ltd | Health & social care | 2016 |
| Intense Paint & Design Limited | Wholesale & retail | 2024 |
| Interled Lighting Limited | Wholesale & retail | 2010 |
| International Payment Services Ltd | Information & communication | 2021 |
| Interpretech Ltd | Information & communication | 2021 |
| Intrada Limited | Other services | 2019 |
| Investigro Limited | Financial services | 2024 |
| Investmentor.Club Limited | Education | 2025 |
| Invite to Paradise Limited | Administrative & support | 2013 |
| Involved Consulting Limited | Professional & scientific | 2016 |
| Iogaciro Limited | Extraterritorial | 2017 |
| Ionian Yefseis Ltd | Hospitality | 2026 |
| IOT Cloud World Limited | Education | 2020 |
| IPG Drivers Ltd | Transport & logistics | 2022 |
| Ipsum M&E Consulting Limited | Professional & scientific | 2019 |
| Irchester Fast Food Ltd | Hospitality | 2025 |
| Irdk Property Management Ltd | Information & communication | 2017 |
| IRH Assessors Ltd | Professional & scientific | 2018 |
| Irth (15) Limited | Administrative & support | 1960 |
| Irth (19) Limited | Professional & scientific | 2002 |
| Irthlingborough Kebab and Burger Ltd | Hospitality | 2026 |
| Irthlingborough Kebab Ltd | Hospitality | 2017 |
| Irthlingborough Pizza Kebab Ltd | Hospitality | 2025 |
| Irthlingborough PUB Limited | Hospitality | 2025 |
| ISA Cars Limited | Transport & logistics | 2025 |
| ISA2 Care and Shine Ltd | Administrative & support | 2019 |
| Isaic ION Ltd | Transport & logistics | 2017 |
| ISE Valley Tyres Limited | Wholesale & retail | 2007 |
| Iseeinvestments Ltd | Wholesale & retail | 2022 |
| Isekony Global Services Ltd | Construction | 2026 |
| Isis Accountants Ltd | Professional & scientific | 2013 |
| Isis Bookkeeping & Payroll Ltd | Professional & scientific | 2014 |
| Isis Business Solutions (Northants) LLP | | 2007 |
| Isis Company Secretarial Services Ltd | Administrative & support | 2005 |
| Isis Life Ltd | Administrative & support | 2014 |
| Isis Payroll & Auto-Enrolment Ltd | Administrative & support | 2014 |
| Isis Payroll Limited | Professional & scientific | 2007 |
| Isis Strategic Management Ltd | Administrative & support | 2014 |
| Isis Tax Accountants LLP | | 2012 |
| Isis Tax Limited | Professional & scientific | 2015 |
| Isis Tax Strategies Ltd | Professional & scientific | 2009 |