| Jasper the PIG Limited | Arts & recreation | 2004 |
| Jasper-Light Limited | Information & communication | 2025 |
| Jastina Properties Ltd | Real estate | 2021 |
| Jasueter Kennels Ltd | Agriculture & fishing | 2017 |
| Jatayu Ltd | Real estate | 2024 |
| Java Associates Ltd | Real estate | 2003 |
| Java Partnership Ltd | Real estate | 2023 |
| Javelin Property Development Limited | Administrative & support | 2013 |
| Javelin Property Management Limited | Administrative & support | 2013 |
| Jaward Properties Ltd | Real estate | 2014 |
| Jaws Pet Services Ltd | Other services | 2026 |
| JAY Concept Limited | Professional & scientific | 2025 |
| JAY Corporation Limited | Financial services | 2018 |
| Jaycee Distributors Limited | Wholesale & retail | 1981 |
| Jaydel Ltd | Real estate | 2023 |
| Jayeness Limited | Administrative & support | 2009 |
| Jayne Bacon PM Consulting (IT) Ltd | Information & communication | 2014 |
| Jaypold Limited | Other services | 2016 |
| Jays Business Services Ltd | Professional & scientific | 2003 |
| Jayscovi Ltd | Extraterritorial | 2017 |
| Jaywilliamsolutions Ltd | Households | 2025 |
| Jazz Carlin Limited | Arts & recreation | 2011 |
| JB Carpentry (Ipswich) Ltd | Construction | 2017 |
| JB Forward Thinking Ltd | Administrative & support | 2016 |
| JB Future Solutions Ltd | Administrative & support | 2013 |
| JB Orwell Ltd | Real estate | 2021 |
| JB Personal Training Ltd | Arts & recreation | 2023 |
| JBA Concept Ltd | Transport & logistics | 2019 |
| Jbbottles Ltd | Wholesale & retail | 2023 |
| JBC Solutions Ltd | Construction | 2026 |
| JBJ Homes Ltd | Real estate | 2015 |
| JBM Accountants Limited | Professional & scientific | 2023 |
| JC Adworks Ltd | Wholesale & retail | 2025 |
| JCA Media Group Limited | Information & communication | 1984 |
| JCA Resilience Group Limited | Financial services | 2020 |
| JCB Accounting Ltd | Professional & scientific | 2020 |
| Jcbcreatives Limited | Administrative & support | 2009 |
| JCF Specialist Care Limited | Health & social care | 2022 |
| JCG Vehicle Services Limited | Wholesale & retail | 2015 |
| Jckd (UK) Ltd | Other services | 2011 |
| JCR Sport Limited | Arts & recreation | 2020 |
| JCS Design Limited | Professional & scientific | 2017 |
| JCS Kinetic Supplies Ltd | Wholesale & retail | 2026 |
| Jcytf Ltd | Transport & logistics | 2016 |
| JD Developments (East Anglia) Ltd | Construction | 2021 |
| JD Flooring Ipswich Ltd | Construction | 2021 |
| JDI Contracts Limited | Professional & scientific | 2007 |
| JDO Branch Limited | Professional & scientific | 2024 |
| JDS Logistics Limited | Transport & logistics | 2014 |
| JDS Suffolk Limited | Water & waste | 2021 |
| JE Happy Gums Ltd | Health & social care | 2025 |
| Je'Se VI Limited | Administrative & support | 2015 |
| JEC Marketing Ltd | Professional & scientific | 2026 |
| Jedhis Limited | Financial services | 2021 |
| Jeetex Limited | Other services | 1982 |
| Jeeves Healthcare Ltd | Wholesale & retail | 2013 |
| Jeff ALI Ltd | Hospitality | 2019 |
| Jehan Ventures Ltd | Wholesale & retail | 2026 |
| Jehe Ltd | Real estate | 2025 |
| Jeian Care Home Limited | Health & social care | 2011 |
| JEL Group Ltd | Construction | 2009 |
| Jellybean Recruitment Ltd | Administrative & support | 2024 |
| JEM (East Anglia) Limited | Real estate | 2014 |
| JEM Property Ipswich Ltd | Real estate | 2020 |
| Jemb Legacy Ltd | Real estate | 2026 |
| Jemway Limited | Other services | 2011 |
| Jenkinson Property Consultants Ltd | Professional & scientific | 2014 |
| Jenlee Limited | Real estate | 2008 |
| Jennings Bros Flooring Ltd | Construction | 2022 |
| Jennings Electrical Ltd | Construction | 2010 |
| Jensen Webb Ltd | Professional & scientific | 2024 |
| Jepson Health Ltd | Health & social care | 2023 |
| Jerai Ltd | Manufacturing | 2020 |
| Jerrard Property Associates Limited | Real estate | 2024 |
| Jess Judd Limited | Arts & recreation | 2013 |
| Jessica Constantin Trans Limited | Transport & logistics | 2020 |
| JET Consulting London Limited | Professional & scientific | 2011 |
| JET Couriers Ltd | Transport & logistics | 2013 |
| JET Delivers Ltd | Transport & logistics | 2012 |
| JET Fulfilment Ltd | Transport & logistics | 2017 |
| JET Prep Ltd | Education | 2024 |
| Jetgroupuk Ltd | Transport & logistics | 2023 |
| Jewelcrest Imports Ltd | Wholesale & retail | 2025 |
| JF Garden & Maintenance Services Ltd | Administrative & support | 2024 |
| JF Play Ltd | Construction | 2022 |
| JF Property Management & Maintenance Ltd Ltd | Real estate | 2024 |
| Jfdi Hospitality Limited | Hospitality | 2024 |
| JFE Complete Wireless Solutions Limited | Information & communication | 2005 |
| JFH Property Services Ltd | Construction | 2026 |
| Jfix Plumbing and Heating Ltd | Construction | 2026 |
| JG Tramper Ltd | Transport & logistics | 2024 |
| Jg&Cc Holdings Limited | Financial services | 2013 |
| JGB Architectural Designs Ltd | Professional & scientific | 2022 |
| JGP East Anglia Ltd | Construction | 2018 |
| JH Health & Care Associates Limited | Health & social care | 2010 |
| JHA Homes Limited | Real estate | 2022 |
| JHB Groundworks Ltd | Construction | 2022 |
| JHP Consultancy Healthcare Limited | Information & communication | 2023 |
| Jigsaw Corporate Financial Management Limited | Financial services | 2010 |
| Jigsaw Recruitment Agency Limited | Administrative & support | 2018 |