| 360 Trade Ltd | Wholesale & retail | 2022 |
| 360 Wheelchairs Ltd | Health & social care | 2019 |
| 360ANDVIBES Limited | Manufacturing | 2022 |
| 360AUTOSUK Ltd | Wholesale & retail | 2024 |
| 360TO360HOLDINGS Ltd | Real estate | 2025 |
| 365 Bridging Ltd | Financial services | 2026 |
| 365 Capital Holdings Ltd | Financial services | 2025 |
| 365 Cloud Security Ltd | Manufacturing | 2026 |
| 365 Computing Limited | Wholesale & retail | 2016 |
| 365 Dept. Limited | Wholesale & retail | 2024 |
| 365 Digital Marketing Limited | Professional & scientific | 2024 |
| 365 Maintenance Members Ltd | Other services | 2025 |
| 365 Protect Ltd | Manufacturing | 2015 |
| 365 Services Limited | Real estate | 2007 |
| 365 Supplies Limited | Wholesale & retail | 2007 |
| 365 Tipper Hire Ltd | Water & waste | 2021 |
| 365/7 Care Limited | Health & social care | 2021 |
| 369 Capital Ltd | Real estate | 2021 |
| 369 Lease Co Limited | Real estate | 2023 |
| 36FAMILIA Ltd | Wholesale & retail | 2019 |
| 37 Group Limited | Arts & recreation | 2019 |
| 37 Jewel Ltd | Real estate | 2024 |
| 37 Properties Limited | Households | 2025 |
| 38 Oakridge Ltd | Hospitality | 2023 |
| 38-54 Walmead Croft RTM Company Limited | Households | 2021 |
| 381 ABS UK Ltd | Professional & scientific | 2011 |
| 383 Project Limited | Professional & scientific | 2006 |
| 39 Hyde Park Gate 1992 Limited | Households | 1992 |
| 39 WM Limited | Hospitality | 2016 |
| 39LS Ltd | Wholesale & retail | 2022 |
| 39SL Ltd | Wholesale & retail | 2024 |
| 3:16 the Well CIC | Education | 2020 |
| 3ALLSTARR Ltd | Wholesale & retail | 2025 |
| 3B1Y Ltd | Hospitality | 2019 |
| 3BALCONIES Limited | Information & communication | 2025 |
| 3BELLE.AMI Health Housing CIC | Public administration | 2025 |
| 3BELLE.AMI Health Limited | Health & social care | 2018 |
| 3BROSPLUS Ltd | Education | 2026 |
| 3C & J Ltd | Wholesale & retail | 2016 |
| 3C Car Parts Ltd | Wholesale & retail | 2017 |
| 3C'S Group Limited | Other services | 2021 |
| 3CC Inc. Ltd | Real estate | 2020 |
| 3D Brickwork Ltd | Construction | 2020 |
| 3D Care Services Limited | Health & social care | 2022 |
| 3D Decorative Plastics (UK) Limited | Manufacturing | 2021 |
| 3D Fitted Furniture Ltd | Manufacturing | 2023 |
| 3D Healthcare Solutions Limited | Health & social care | 2015 |
| 3D Housing Group Ltd | Real estate | 2020 |
| 3D in Care Ltd | Health & social care | 2014 |
| 3D Interiors Midlands Limited | Wholesale & retail | 2026 |
| 3D News Ltd | Wholesale & retail | 2025 |
| 3D Plant and Machinery Limited | Administrative & support | 1993 |
| 3D Properties Investment Limited | Real estate | 2024 |
| 3D Property Services Ltd | Real estate | 2023 |
| 3D Timberworks Ltd | Manufacturing | 2025 |
| 3D'S Cleaning Solutions Ltd | Administrative & support | 2026 |
| 3DFIY Ltd | Wholesale & retail | 2025 |
| 3DVIEWERONLINE Ltd | Information & communication | 2016 |
| 3DXY Ltd | Wholesale & retail | 2023 |
| 3E Innovation Labs Ltd | Professional & scientific | 2026 |
| 3E Value for Money Ltd | Information & communication | 2016 |
| 3ELEMENT Covers Limited | Manufacturing | 2022 |
| 3H Business Management Limited | Real estate | 2024 |
| 3H Leasehold Limited | Real estate | 2023 |
| 3H Media Production Ltd | Information & communication | 2021 |
| 3HEADS1SOLUTION Limited | Hospitality | 2017 |
| 3HOLD Property Investments Ltd | Real estate | 2025 |
| 3HR Ltd | Financial services | 2023 |
| 3JN Property Ltd | Real estate | 2025 |
| 3KIN Ltd | Other services | 2016 |
| 3KLAPS Business Solutions Ltd | Information & communication | 2008 |
| 3LANCE Marketing Limited | Professional & scientific | 2025 |
| 3LIGHTMEDIA Limited | Information & communication | 2015 |
| 3LIGHTTALENT Limited | Information & communication | 2025 |
| 3LMK Limited | Financial services | 2020 |
| 3M Enterprise HQ Ltd | Administrative & support | 2026 |
| 3M Estates Limited | Real estate | 2022 |
| 3M Property Holding Group Ltd | Real estate | 2020 |
| 3M Property Sourcing Limited | Administrative & support | 2023 |
| 3MA Holdings Limited | Professional & scientific | 2019 |
| 3MK Ltd | Real estate | 2014 |
| 3MS Gold Services Limited | Construction | 2007 |
| 3MTECH Ltd | Wholesale & retail | 2023 |
| 3N'S Dorchester Ltd | Hospitality | 2015 |
| 3NAS Ltd | Construction | 2026 |
| 3NEWSTART Limited | Hospitality | 2024 |
| 3P Foods Ltd | Hospitality | 2016 |
| 3P Housing Ltd | Real estate | 2026 |
| 3R Buildings Limited | Real estate | 2020 |
| 3R Global Talent Ltd | Administrative & support | 2024 |
| 3RD Dimension Ltd | Professional & scientific | 2019 |
| 3RD EYE Data Consulting Ltd | Information & communication | 2020 |
| 3SIXTY Consultancy Services Ltd | Information & communication | 2019 |
| 3SIXTY Creative Marketing Solutions Ltd | Professional & scientific | 2011 |
| 3SIXTY Restaurants Limited | Hospitality | 2011 |
| 3SIXTYFIVESERVICES Ltd | Transport & logistics | 2025 |
| 3SPR Management Services Ltd | Professional & scientific | 2015 |
| 3WILLOWS Limited | Construction | 2014 |
| 3XM Marketing Ltd | Professional & scientific | 2023 |
| 3XM Marketing Partners LLP | | 2023 |