| Z&M Pure Threads & Tots Limited | Wholesale & retail | 2025 |
| ZA Solutions Limited | Professional & scientific | 2009 |
| Zaar Living Ltd | Manufacturing | 2024 |
| Zacharias Limited | Hospitality | 2018 |
| Zacks Catering Limited | Hospitality | 2017 |
| Zacks Enterprise Limited | Wholesale & retail | 2020 |
| Zagaroli Limited | Administrative & support | 2016 |
| ZAK Mobiles Ltd | Wholesale & retail | 2024 |
| ZAR & KA Properties Ltd | Real estate | 2022 |
| ZAY Aesthetics Ltd | Other services | 2020 |
| ZBQ Properties Ltd | Real estate | 2018 |
| ZED Education Group Limited | Education | 2025 |
| Zedest Limited | Administrative & support | 2007 |
| Zenith Healing Crystals Limited | Information & communication | 2014 |
| Zenith Learning Partnership Limited | Health & social care | 2025 |
| Zestika Events Ltd | Hospitality | 2025 |
| Zeus UK Holdings Limited | Financial services | 2023 |
| ZFS Ltd | Financial services | 2018 |
| Zhdk Ltd | Health & social care | 2024 |
| Zhou Accountancy Ltd | Professional & scientific | 2016 |
| ZI Jackson Ltd | Administrative & support | 2022 |
| Zigigrowth Limited | Administrative & support | 2026 |
| Zinc Information Centre | Other services | 2001 |
| Zinkt Ltd | Professional & scientific | 2019 |
| Zintelli Ltd | Information & communication | 2023 |
| Zion Farming Limited | Agriculture & fishing | 2020 |
| Zionas Ltd | Construction | 2017 |
| Zipho Holdings Ltd | Health & social care | 2016 |
| Zkurea Ltd | Information & communication | 2022 |
| ZM Real Estates Ltd | Real estate | 2024 |
| ZMB Asset Management Ltd | Real estate | 2022 |
| Zoltar Classic Ltd | Wholesale & retail | 2022 |
| Zoltar Consulting Ltd | Professional & scientific | 2019 |
| Zone Two Group Ltd | Wholesale & retail | 2023 |
| Zoomies Dog Daycare Ltd | Agriculture & fishing | 2024 |
| Zoras Capital Limited | Real estate | 2026 |
| Zoras Medics Ltd | Health & social care | 2018 |
| Zorba TDR Ltd | Information & communication | 2021 |
| Zorbas Restaurant Limited | Hospitality | 2010 |
| Zordar Limited | Extraterritorial | 2012 |
| ZR (Midlands) Ltd | Hospitality | 2018 |
| ZSA Traders Ltd | Health & social care | 2008 |
| Zurowest Ltd | Wholesale & retail | 2025 |
| ZWR PEO Ltd | Professional & scientific | 2025 |
| ZX Peterborough Developments Ltd | Construction | 2021 |
| Zycon Consulting Limited | Wholesale & retail | 2022 |
| Zyvra Studio Ltd | Information & communication | 2026 |
| Øutlaw Clothing Ltd | Wholesale & retail | 2024 |