| Yeend Close Management Limited | Households | 2007 |
| Yelco Holding Company Limited | Financial services | 2023 |
| Yeldeh Group Limited | Real estate | 2016 |
| Yelloknots Studio Ltd | Professional & scientific | 2025 |
| Yellow 175 Ltd | Wholesale & retail | 2026 |
| Yeltarp Ltd. | Construction | 2026 |
| YES Africa Limited | Professional & scientific | 2004 |
| YES Lets! (London) Limited | Real estate | 2008 |
| YES to DYE Ltd | Administrative & support | 2019 |
| Yeshiva Formation Talmidim Ltd | Education | 2010 |
| YG Software Consultancy Ltd | Information & communication | 2014 |
| Yida Media Co., Ltd | Wholesale & retail | 2025 |
| Yield AI Ltd | Information & communication | 2026 |
| Yiewsley Canal View Management Limited | Construction | 2011 |
| Yigit Industrial & Trading Limited | Manufacturing | 2026 |
| Yinhe Culture ME Ltd | Wholesale & retail | 2025 |
| Yiro Ltd | Hospitality | 2015 |
| Yiwu ATQ Market Purchasing Co., Ltd | Wholesale & retail | 2023 |
| Yiwu Changrui Import & Export Co., Limited | Wholesale & retail | 2024 |
| Yiwu Gazan Global Co., Limited | Wholesale & retail | 2025 |
| Yiwu Mingfan Import & Export Co., Ltd | Wholesale & retail | 2021 |
| Yiwu Mulin IMP. & EXP. Co., Limited | Wholesale & retail | 2023 |
| Yiwu Sabawoon Trading Co., Ltd | Manufacturing | 2025 |
| Yiwu Shanhushu Trading Co., Ltd | Wholesale & retail | 2024 |
| Yiwu Tingshen Trading Co., Ltd | Wholesale & retail | 2025 |
| Yiwu Weijie Co., Ltd | Wholesale & retail | 2023 |
| Yiwu Yanyun Trading Co., Ltd | Wholesale & retail | 2025 |
| YJS Consultancy Services Ltd | Information & communication | 2017 |
| YK Glamour Hair Ltd | Other services | 2025 |
| Ykam Limited | Real estate | 2021 |
| YKH Global Trading Ltd | Wholesale & retail | 2024 |
| YKR Ltd | Hospitality | 2023 |
| YLM Enterprise Limited | Public administration | 2019 |
| YMY Limited | Information & communication | 2024 |
| Ynes Solutions Ltd | Administrative & support | 2026 |
| Ynys Properties Limited | Real estate | 2021 |
| YO Rail Ltd | Construction | 2023 |
| Yocheved Limited | Professional & scientific | 2015 |
| Yogarajah & Vaani Limited | Wholesale & retail | 2022 |
| Yogayet Flat Management Company Limited | Households | 1978 |
| Yolakuizin Ltd | Hospitality | 2026 |
| Yomaa Ltd | Real estate | 2018 |
| Yoova Homes Ltd | Construction | 2020 |
| Yorgos Panagopoulos Design Limited | Professional & scientific | 2024 |
| York Club Management Limited | Households | 2017 |
| York Investment Properties Limited | Real estate | 2021 |
| York Road Property Investment Ltd | Real estate | 2025 |
| Yorkmoor Property Management (Anerley) Ltd | Administrative & support | 2006 |
| Yormetiam Legacy Properties Ltd | Real estate | 2025 |
| Yoro Properties Ltd | Administrative & support | 2025 |
| YOU CAN Associates Limited | Administrative & support | 2008 |
| YOU Know ME Media Ltd | Information & communication | 2024 |
| Youchoosecare Ltd | Health & social care | 2024 |
| Youlookbooked Ltd | Information & communication | 2026 |
| Young Roots | Health & social care | 2010 |
| Young Team Ltd | Other services | 2026 |
| Youngevity UK Ltd | Health & social care | 2019 |
| Youngstars Nurseries (Addlestone) Limited | Health & social care | 2020 |
| Your Choice Building Construction Services Ltd | Construction | 2024 |
| Your Healthy Life Group Ltd | Wholesale & retail | 2025 |
| Your Healthy Life Limited | Other services | 2017 |
| Your Home OUR Home Ltd | Hospitality | 2017 |
| Your London Pet Sitter Ltd | Other services | 2016 |
| Your Marketing Assitant Limited | Administrative & support | 2018 |
| Your Office Search Limited | Professional & scientific | 2023 |
| Your Page Ltd | Professional & scientific | 2023 |
| Your Property Search Ltd | Professional & scientific | 2020 |
| Your Service Guard Limited | Information & communication | 2025 |
| Your Solution Healthcare Professionals Limited | Health & social care | 2023 |
| Your Soul Reforms Ltd | Health & social care | 2025 |
| Yourious Ltd | Wholesale & retail | 2019 |
| Yourstor (Surrey) Limited | Transport & logistics | 2019 |
| Yourstor Limited | Transport & logistics | 2017 |
| Youth Care Ltd | Health & social care | 2018 |
| Youth Organisation Undertaking National Growth Ltd. | Education | 2016 |
| Youthallot Ltd | Education | 2024 |
| Yphsimple Ltd | Wholesale & retail | 2024 |
| YRB News Market Limited | Wholesale & retail | 2024 |
| YS Advanced Clinical Practice Limited | Health & social care | 2022 |
| YS Croydon Autos Ltd | Wholesale & retail | 2025 |
| Ysfsupply Ltd | Wholesale & retail | 2026 |
| YSN Catering Limited | Hospitality | 2026 |
| YSN Lettings Limited | Real estate | 2010 |
| Ytt&T Medical Limited | Health & social care | 2014 |
| Yuanwan Culture Media Ltd | Wholesale & retail | 2025 |
| Yuanxin Media Co., Ltd | Wholesale & retail | 2025 |
| Yufa Fast Food Limited | Hospitality | 2017 |
| Yukon Toddlers & Pre-School Ltd | Education | 2014 |
| YUM Ceuticals Ltd | Wholesale & retail | 2023 |
| Yumn Limited | Hospitality | 2016 |
| Yumzi Ltd | Hospitality | 2026 |
| Yunus Dilek Epos Systems Ltd | Wholesale & retail | 2025 |
| Yurong Supply Chain Ltd | Wholesale & retail | 2025 |
| Yusbel London Limited | Other services | 2019 |
| Yuteng Media Ltd | Wholesale & retail | 2024 |
| Yuva Talents Ltd | Administrative & support | 2023 |
| Yuvan Ltd | Construction | 2026 |
| YV Trucking Ltd | Transport & logistics | 2019 |
| Yvette Health Care Ltd | Health & social care | 2014 |
| Yvonne's Care Ltd | Health & social care | 2026 |