| 1ST Solutions INT Ltd | Education | 2020 |
| 1ST Source Limited | Other services | 2026 |
| 1ST South Limited | Other services | 2024 |
| 1ST Space Ltd | Real estate | 2025 |
| 1ST Sports Ltd | Arts & recreation | 2015 |
| 1ST Start Services Limited | Other services | 2026 |
| 1ST Stay Ltd | Real estate | 2024 |
| 1ST Step Consulting Ltd | Professional & scientific | 2023 |
| 1ST Step Managment Ltd | Information & communication | 2022 |
| 1ST Stepping Stone Limited | Real estate | 2003 |
| 1ST Stepping Stones Nursery School Limited | Health & social care | 2018 |
| 1ST Stop Accountancy and Tax Services Bristol Limited | Professional & scientific | 2016 |
| 1ST Stop Builders Ltd | Construction | 2019 |
| 1ST Stop Contractors Limited | Construction | 2017 |
| 1ST Stop Investments Limited | Real estate | 2012 |
| 1ST Stop Kebab Limited | Hospitality | 2025 |
| 1ST Stop Property Holdings Great Yarmouth Ltd | Real estate | 2026 |
| 1ST Stop Property Holdings Limited | Real estate | 2017 |
| 1ST Stop Security Systems Ltd | Construction | 2018 |
| 1ST Stop Stationers Limited | Wholesale & retail | 1993 |
| 1ST Stroke Decorators Ltd | Construction | 2024 |
| 1ST Style Limited | Wholesale & retail | 2024 |
| 1ST Systems Limited | Other services | 2026 |
| 1ST Take Ltd | Information & communication | 2005 |
| 1ST Talent Ltd | Professional & scientific | 2013 |
| 1ST Tech Advance Limited | Information & communication | 2026 |
| 1ST Tech Limited | Other services | 2022 |
| 1ST Technologies Group Ltd | Financial services | 2025 |
| 1ST Telecom Alarms Limited | Real estate | 2000 |
| 1ST Time Maintenance Ltd | Administrative & support | 2015 |
| 1ST to SET Ltd | Arts & recreation | 2023 |
| 1ST Traders Limited | Financial services | 2021 |
| 1ST Trading Ltd | Wholesale & retail | 2019 |
| 1ST Tuition Limited | Education | 2015 |
| 1ST UK Choice Limited | Transport & logistics | 2005 |
| 1ST UK Roofing & Building Ltd | Construction | 2019 |
| 1ST UK Traders Limited | Other services | 2025 |
| 1ST Ukimmigration Lawyers-Dm Law Practice Ltd. | Professional & scientific | 2016 |
| 1ST Union Holding Limited | Financial services | 2023 |
| 1ST Union Property Ltd | Real estate | 2017 |
| 1ST Unique Developments Limited | Real estate | 2017 |
| 1ST Vine Ltd | Real estate | 2022 |
| 1ST Visa International Limited | Professional & scientific | 2022 |
| 1ST West Limited | Other services | 2024 |
| 1ST World Services Limited | Other services | 2026 |
| 1ST World Systems Limited | Other services | 2022 |
| 1ST World Textile Limited | Manufacturing | 2025 |
| 1ST XV Films Limited | Information & communication | 2011 |
| 1ST-ENT Limited | Health & social care | 2013 |
| 1ST. Choice Cleaning Limited | Administrative & support | 2001 |
| 1ST. Data Limited | Other services | 2026 |
| 1ST.TECHNOLOGY LP | | 2019 |
| 1ST24 Ltd | Information & communication | 2024 |
| 1START Trading Limited | Wholesale & retail | 2019 |
| 1STAVEMACHINEUK Ltd | Information & communication | 2021 |
| 1STAYS (Bravo) Limited | Real estate | 2025 |
| 1STBABIES Ltd | Wholesale & retail | 2025 |
| 1STCHAUFFEUR Ltd | Transport & logistics | 2026 |
| 1STCHOICE Company Formations Ltd | Other services | 2018 |
| 1STCO Services UK Ltd | Professional & scientific | 2023 |
| 1STEIGHT Ltd | Real estate | 2023 |
| 1STEIGHTEEN Ltd | Information & communication | 2025 |
| 1STEP2MARKET Limited | Information & communication | 2020 |
| 1STEP4FUTURE Ltd | Professional & scientific | 2025 |
| 1STEPAHEAD Global Services Ltd | Professional & scientific | 2020 |
| 1STFIT Construction Ltd | Construction | 2026 |
| 1STOP Computer Repairs Ltd | Wholesale & retail | 2019 |
| 1STOP ICT Solutions Ltd | Information & communication | 2020 |
| 1STOP Offshore Drilling Services Ltd | Mining & quarrying | 2025 |
| 1STOPBABYSTORE Ltd | Arts & recreation | 2015 |
| 1STOPDESIGNANDBUILD Ltd | Construction | 2023 |
| 1STOPMONEYHELP Ltd | Administrative & support | 2025 |
| 1STOPPERFUMESHOP Ltd | Wholesale & retail | 2023 |
| 1STOPSALES Limited | Professional & scientific | 2017 |
| 1STOPSHOP4U Ltd | Wholesale & retail | 2025 |
| 1STOPSHOPPING Ltd | Wholesale & retail | 2025 |
| 1STOPVAT UK Ltd | Professional & scientific | 2023 |
| 1STOPXBRL Limited | Professional & scientific | 2012 |
| 1STPICKJEMZ Ltd | Wholesale & retail | 2025 |
| 1STSOLUTIONS Ltd | Information & communication | 2021 |
| 1SW Events London Ltd | Professional & scientific | 2018 |
| 1SWAP Limited | Information & communication | 2025 |
| 1T Support Ltd | Information & communication | 2021 |
| 1TABLE Limited | Professional & scientific | 2024 |
| 1TAP App Limited | Information & communication | 2016 |
| 1TEN Marketing Ltd | Professional & scientific | 2021 |
| 1TNE Ltd | Wholesale & retail | 2021 |
| 1TO1 Books Ltd | Information & communication | 2025 |
| 1TOO8 Ltd | Households | 2023 |
| 1TOP Stop Limited | Financial services | 2025 |
| 1TR Development Ltd | Construction | 2022 |
| 1TRIGGER Ltd | Wholesale & retail | 2025 |
| 1TST Limited | Real estate | 2024 |
| 1TWO1 Services and Allied Limited | Information & communication | 2026 |
| 1TWO4 Productions Ltd | Information & communication | 2024 |
| 1TWOAPPS Limited | Information & communication | 2022 |
| 1U Consulting Limited | Professional & scientific | 2026 |
| 1UKACCESS Ltd | Water & waste | 2025 |
| 1UP Construction Ltd | Construction | 2023 |
| 1UP Enterprise Limited | Wholesale & retail | 2020 |