| Intumescent Paint Specialists Limited | Construction | 2018 |
| IPM Solutions Limited | Information & communication | 2021 |
| Iris Galleries Limited | Wholesale & retail | 2002 |
| Ironclad Craft Brews Limited | Administrative & support | 2023 |
| Island Tyres Ltd | Wholesale & retail | 2023 |
| Island UK Limited | Transport & logistics | 2009 |
| Island UK Logistics Limited | Wholesale & retail | 2021 |
| Ismet Medi Ltd | Construction | 2025 |
| Ivor Copeland Ltd | Construction | 2003 |
| J & a Props Limited | Information & communication | 2015 |
| J Smithers Catering Ltd | Hospitality | 2024 |
| J.M Properties 24 Ltd | Construction | 2024 |
| Jack Vintage Ltd | Wholesale & retail | 2013 |
| Jacket Required (Hayling) Ltd | Hospitality | 2020 |
| Jalid Limited | Hospitality | 2021 |
| James Court (Hayling Island) Management Limited | Households | 1986 |
| JD Design Ltd | Other services | 2017 |
| Jimmy Blandford Recycling Ltd | Water & waste | 2025 |
| Jiva Hampshire Property Ltd | Real estate | 2021 |
| Jiva Healthcare Hampshire Limited | Health & social care | 2017 |
| JJH Building Services Limited | Real estate | 2013 |
| JJJ Renewables Limited | Energy | 2025 |
| JM Builders and Carpentry Ltd | Construction | 2024 |
| Jmcr Holdings Limited | Professional & scientific | 2008 |
| JO Hamilton Interiors Limited | Professional & scientific | 2017 |
| John E Engineering Ltd | Professional & scientific | 2013 |
| Jonathan Andrews Services Limited | Construction | 2026 |
| Jones Brothers (Flat Roofing) Limited | Construction | 1992 |
| JT Industrial Roofing and Cladding Ltd | Construction | 2015 |
| Jubayl Investments Limited | Manufacturing | 2008 |
| Just Jones & | Arts & recreation | 2011 |
| K.& J.Builders(Hounslow)Limited | Construction | 1966 |
| Kalfas Services Limited | Transport & logistics | 2019 |
| Kali Clinic Medical Grade Skin Limited | Other services | 2025 |
| Kavya & Tanisha Ltd | Wholesale & retail | 2025 |
| Kempy Leisure Limited | Hospitality | 2021 |
| Kenilworth House Residents Limited | Real estate | 2021 |
| Ken’S Niyom Thai Limited | Hospitality | 2021 |
| Khushi Eastoke Ltd | Wholesale & retail | 2022 |
| Kingsbury Mansions Management Company Limited | Households | 2023 |
| Kingsdale Consultancy Limited | Administrative & support | 2011 |
| Kiwi Blends Limited | Wholesale & retail | 2024 |
| Konsept Services Limited | Professional & scientific | 2012 |
| Kost Radio Ltd | Information & communication | 2024 |
| KPM Roofing Limited | Construction | 2022 |
| KR Technology Innovation and Design Ltd | Information & communication | 2016 |
| L&G Properties (South) Ltd | Households | 2022 |
| L.Isaac & Sons Limited | Hospitality | 2023 |
| Laarp Ltd | Hospitality | 2023 |
| Labeldene Limited | Professional & scientific | 1987 |
| Lama Court Management Limited | Households | 2025 |
| Langrish Property Ltd | Real estate | 2016 |
| Lauras House Ltd | Hospitality | 2024 |
| Lauren Mews (Management) Company Limited | Households | 1999 |
| Leah MEW Architecture Ltd | Professional & scientific | 2021 |
| Leargold Limited | Other services | 1991 |
| Lees Lucky 13 Auto Body and Paint Ltd | Wholesale & retail | 2019 |
| Legal Recruitment Solutions Limited | Professional & scientific | 2018 |
| Leyson Data Limited | Information & communication | 2002 |
| Liakada Imports Exports Ltd | Wholesale & retail | 2023 |
| Life After Flash Ltd | Information & communication | 2018 |
| Life After Movies Ltd | Information & communication | 2020 |
| Lilley Architecture Limited | Professional & scientific | 2011 |
| Lintel Build Ltd | Information & communication | 2026 |
| Linton Jones Limited | Arts & recreation | 2014 |
| Little Lambs Nursery (Portsmouth) Ltd | Health & social care | 2019 |
| Little Ship Projects Limited | Administrative & support | 2008 |
| Littlemead Investments Ltd | Real estate | 2011 |
| London and County Homes Limited | Construction | 2005 |
| LOS Amigos Familia Ltd | Hospitality | 2024 |
| Lothian Consultancy Ltd | Professional & scientific | 2019 |
| Lower TYE Farm Limited | Extraterritorial | 1966 |
| LT Clerk of Works Ltd | Construction | 2020 |
| Ltps Services Ltd | Transport & logistics | 2025 |
| LUCAS11 Ltd | Professional & scientific | 2021 |
| Lulu's Hayling Limited | Hospitality | 2024 |
| M Byrne Composites Ltd | Construction | 2025 |
| M D Barnett Carpentry and Building Limited | Construction | 2023 |
| M L Wakely Electrical Limited | Construction | 2007 |
| M.P.R Multi Services Ltd | Other services | 2011 |
| Malco Management Limited | Construction | 2017 |
| Mall 55 Ltd | Education | 2023 |
| Mamlambo Limited | Professional & scientific | 2014 |
| Manby Bio-Cng Production (1) Limited | Water & waste | 2022 |
| Marathon Leisure Ltd | Wholesale & retail | 1992 |
| Marine Property Management Ltd | Other services | 2017 |
| Mark Dineen & Co Limited | Professional & scientific | 2004 |
| Marsh Forbes Limited | Professional & scientific | 2011 |
| Marston Solutions Limited | Information & communication | 2013 |
| Martin Leaning Masts & Rigging Limited | Administrative & support | 2000 |
| Mastercraft Automotive Ltd | Wholesale & retail | 2020 |
| Maudes Investments Ltd. | Real estate | 1948 |
| MAV Portsmouth Ltd | Administrative & support | 2025 |
| Mawson Investments Ltd | Real estate | 2021 |
| MAX Grealey GAS, Heating & Plumbing Ltd | Construction | 2019 |
| Mckelvie Productions Ltd | Arts & recreation | 2026 |
| MDP Security {Southern} Ltd | Administrative & support | 2022 |
| Meath Estates (1994) Limited | Households | 1994 |
| Medina Joinery Limited | Manufacturing | 2006 |
| Medway Homes (NO.1) Ltd | Construction | 2025 |