| Xynamo 5 Limited | Professional & scientific | 2018 |
| XZO Limited | Other services | 2025 |
| Y DIY Limited | Construction | 2021 |
| Y&D International Consulting Limited | Professional & scientific | 2011 |
| Y.A.P TCG Limited | Wholesale & retail | 2025 |
| Y.I.A. Limited | Health & social care | 2018 |
| Y.K Design Limited | Professional & scientific | 2015 |
| Yaboye Logistic & Procurement Ltd | Wholesale & retail | 2021 |
| Yachting Power Ltd | Manufacturing | 2020 |
| Yagnaraman Ltd | Wholesale & retail | 2022 |
| YAP Global Ltd | Professional & scientific | 2018 |
| Yap-Jacobsson Holdings Ltd | Financial services | 2022 |
| Yap-Jacobsson Property Limited | Real estate | 2020 |
| Yardan Medical Limited | Health & social care | 2010 |
| Yasmin Spice Ltd | Hospitality | 2020 |
| YASMINA96 Ltd | Hospitality | 2026 |
| Yatta Studio Ltd | Arts & recreation | 2022 |
| Yeablood Entertainment Group Ltd | Wholesale & retail | 2012 |
| Yellow Bird Accountancy Limited | Professional & scientific | 2022 |
| YES Promo Products Limited | Administrative & support | 2011 |
| YES YOU CAN Ltd | Administrative & support | 2018 |
| YET Another Investment Company Ltd | Financial services | 2025 |
| YEW Tree Residents Association Company Limited | Households | 2020 |
| YH Tooth Fairy Limited | Health & social care | 2024 |
| Ymed Limited | Health & social care | 2006 |
| Ymvora Holdings Limited | Financial services | 2020 |
| Yogeeraj Limited | Wholesale & retail | 2023 |
| Yoke Network Ltd | Professional & scientific | 2018 |
| Yoku Catering Ltd | Hospitality | 2024 |
| Yoldas Ltd | Hospitality | 2022 |
| Yoon W Ltd | Health & social care | 2024 |
| York Mansions (Battersea Park) Limited | Professional & scientific | 1982 |
| Yoshino & Co. (U.K.) Limited | Wholesale & retail | 1984 |
| YOU Just Lost the Game Ltd | Information & communication | 2021 |
| Youlogy Ltd | Other services | 2025 |
| Young Haymakers Limited | Health & social care | 2012 |
| Young Medical Limited | Health & social care | 2022 |
| Youngman Developments Limited | Real estate | 2025 |
| Your Creative Force CIC | Arts & recreation | 2014 |
| Your Eastbourne BID Limited | Other services | 2019 |
| Your Guitar Academy Ltd | Education | 2014 |
| YRT Investments Limited | Real estate | 2019 |
| YUG Solutions Ltd | Information & communication | 2024 |
| Yummy Noodles Limited | Hospitality | 2024 |
| YYC Portfolio 2 Ltd | Administrative & support | 2020 |
| Zaarhyaan Ltd | Professional & scientific | 2025 |
| Zaash Holdings Ltd | Real estate | 2025 |
| ZAC J Media Ltd | Information & communication | 2025 |
| Zadok's Studio Limited | Arts & recreation | 2010 |
| Zakynthos Limited | Health & social care | 2020 |
| ZAP Occupational Therapy Ltd | Health & social care | 2019 |
| ZAP OFF Licence Ltd | Wholesale & retail | 2020 |
| Zara Jewellers Limited | Wholesale & retail | 2018 |
| Zendta Ltd | Information & communication | 2019 |
| Zenon Aviation Ltd | Transport & logistics | 2012 |
| Zenon Aviation Recruitment Limited | Administrative & support | 2013 |
| Zerlo Limited | Health & social care | 2020 |
| Zest Cleaning Ltd | Administrative & support | 2026 |
| Zimple Group Limited | Administrative & support | 2021 |
| Zinart Co Ltd | Households | 2019 |
| Zinir Limited | Professional & scientific | 2003 |
| Ziraf Ltd | Information & communication | 2017 |
| Zlatkov Carpentry and Building Ltd | Construction | 2026 |
| Zone Eastbourne Ltd | Arts & recreation | 2025 |
| Zonio Ltd | Health & social care | 2025 |
| Zoonou Limited | Information & communication | 2006 |
| Zoonou Trustees Limited | Administrative & support | 2023 |
| Zovo Sports Limited | Wholesale & retail | 2025 |
| ZRM Healthcare Limited | Health & social care | 2021 |
| ZTR Investments Limited | Real estate | 2016 |
| Zukuri Capital Limited | Financial services | 2021 |
| Zuma G Ltd | Administrative & support | 2025 |
| Zunoma Holdings Ltd | Financial services | 2026 |
| Zunoma Investments Ltd | Real estate | 2026 |
| Zunoma Property Ltd | Real estate | 2026 |
| Zyskowska Property Limited | Real estate | 2024 |