| WT Limited | Manufacturing | 2005 |
| Wulfwear Clothing Ltd | Wholesale & retail | 2017 |
| Wundia Ltd | Real estate | 2019 |
| Wwags International Ltd | Professional & scientific | 2022 |
| Wwags Studio Limited | Professional & scientific | 2016 |
| Wycombe Water Limited | Wholesale & retail | 1999 |
| Wyndley Pensions Limited | Financial services | 2017 |
| Wynsing Graphics Limited | Administrative & support | 1973 |
| Wyrd Designz Ltd | Manufacturing | 2020 |
| Wyrd R&D Ltd | Manufacturing | 2026 |
| Wyzeup.Com Limited | Hospitality | 2001 |
| X-Twenty Ltd | Professional & scientific | 2026 |
| Xanders Services (Herts) LLP | | 2014 |
| Xcelerate Leasing Ltd | Administrative & support | 2022 |
| Xcellant Services Limited | Professional & scientific | 2023 |
| Xcite Ignite Ltd | Professional & scientific | 2024 |
| Xeometry Ltd | Arts & recreation | 2024 |
| Xevyte Technologies Limited | Information & communication | 2022 |
| Xhakola Ltd | Wholesale & retail | 2024 |
| XML Sitemaps Limited | Information & communication | 2014 |
| Xoom IT Limited | Information & communication | 2017 |
| XPA Logistic Ltd | Transport & logistics | 2019 |
| Xpress Labels Limited | Manufacturing | 2000 |
| Xpress Route Couriers Ltd | Transport & logistics | 2025 |
| XR Future Ltd | Information & communication | 2025 |
| Y I Consulting Ltd | Financial services | 2012 |
| Y&L Consulting Limited | Information & communication | 2025 |
| Y.V.M. Ltd | Other services | 2015 |
| Yaas Trading Limited | Wholesale & retail | 2025 |
| Yaka 18 Ltd | Wholesale & retail | 2020 |
| Yalla Catering Limited | Hospitality | 2021 |
| Yanis Ariciu Gardening Ltd | Administrative & support | 2021 |
| Yard Events Ltd | Hospitality | 2025 |
| Yashi Limited | Construction | 2026 |
| Yeat Investments Limited | Real estate | 2014 |
| Yehowada Limited | Health & social care | 2010 |
| Yellow Parrot Ltd | Wholesale & retail | 2018 |
| Yellow Petal Ltd | Manufacturing | 2021 |
| Yeoyo Ltd | Wholesale & retail | 2023 |
| YES2THERAPY Ltd | Health & social care | 2026 |
| Yeung Holdings LLP | | 2025 |
| YEW Lettings Limited | Real estate | 2022 |
| YEW Tree Client Services Limited | Professional & scientific | 2020 |
| YEW Tree Court Management Co. Limited | Households | 1989 |
| YH Advisory Ltd | Professional & scientific | 2025 |
| Yinkactive Ltd | Administrative & support | 2025 |
| Ymia Food Limited | Hospitality | 2025 |
| YN Investments Ltd | Extraterritorial | 2015 |
| YO Donuts Aylesbury Ltd | Hospitality | 2023 |
| YO Doughnuts Ltd | Hospitality | 2026 |
| Yoga Annie Limited | Arts & recreation | 2017 |
| Yoga Studio Limited | Professional & scientific | 2001 |
| Yokub Cars Ltd | Administrative & support | 2025 |
| Yoonik Speshel Care Ltd | Health & social care | 2022 |
| Yoredale Associates Limited | Professional & scientific | 2019 |
| Yoresa Limited | Professional & scientific | 2020 |
| York Residential Ltd | Real estate | 2021 |
| Yostrato Ltd | Information & communication | 2016 |
| YOU Want Beef (Aylesbury) Ltd | Hospitality | 2022 |
| Youell Capital Limited | Real estate | 2016 |
| Young Accountancy & Co Ltd | Professional & scientific | 2013 |
| Young Blood Muscle Ltd | Extraterritorial | 2019 |
| Young Performing Artists Limited | Education | 2026 |
| Youngcreatorsstudio Limited | Education | 2024 |
| Your Choice Health Care Ltd | Administrative & support | 2016 |
| Your Event Music Limited | Arts & recreation | 2016 |
| Your Housekeeper Limited | Administrative & support | 2024 |
| Your Menopause Limited | Extraterritorial | 2026 |
| Your Project Support Limited | Professional & scientific | 2012 |
| Your Vision Media Limited | Information & communication | 2018 |
| Yourgolfbooking.Com Ltd | Arts & recreation | 2011 |
| Youth Club Ltd | Other services | 2024 |
| Youth Concern Enterprise Ltd | Real estate | 2026 |
| Youth Visionaries CIC | Education | 2025 |
| Yuktha Systems Ltd | Information & communication | 2014 |
| YVS Haulage & Transportation Ltd | Transport & logistics | 2023 |
| Z M Welder Ltd | Other services | 2020 |
| Zackoffers Ltd | Wholesale & retail | 2026 |
| Zafarrancho Ltd | Professional & scientific | 2021 |
| ZAK Good Carpentry Ltd | Construction | 2025 |
| Zakya Consulting Limited | Extraterritorial | 2020 |
| Zala Holdings Limited | Financial services | 2021 |
| Zala International Ltd | Wholesale & retail | 2020 |
| Zala Investments Ltd | Real estate | 2021 |
| Zalanda Ltd | Wholesale & retail | 2023 |
| Zaman Architects Ltd | Professional & scientific | 2024 |
| Zara Bibi Properties Limited | Real estate | 2024 |
| Zara Clean Ltd | Professional & scientific | 2019 |
| Zataso Limited | Real estate | 2021 |
| Zazu Digital Ltd | Administrative & support | 2018 |
| Zcorp Consultancy Ltd | Financial services | 2022 |
| Zeemak Energy Ltd | Professional & scientific | 2018 |
| Zening IT Limited | Information & communication | 2023 |
| Zenith 27 Limited | Real estate | 2024 |
| Zenith B Installations Limited | Manufacturing | 2015 |
| Zenza Energy Limited | Professional & scientific | 2025 |
| Zerhoun Commerce Ltd | Wholesale & retail | 2026 |
| Zerotoproduct Limited | Professional & scientific | 2026 |
| Zetafine Commercial Limited | Professional & scientific | 1994 |
| Zeteo Homes Limited | Real estate | 2024 |