| Welwyn Change Partners Limited | Professional & scientific | 2022 |
| Welwyn Construction Ltd | Construction | 2015 |
| Welwyn DIY Limited | Wholesale & retail | 2013 |
| Welwyn Eastbridge Ltd | Wholesale & retail | 2021 |
| Welwyn Escape Rooms Ltd | Arts & recreation | 2022 |
| Welwyn Fast Food T/A FAT Jacks and Downtown Pizza Ltd | Hospitality | 2025 |
| Welwyn Festival Association Limited(The) | Arts & recreation | 1940 |
| Welwyn Fine Food Ltd | Hospitality | 2020 |
| Welwyn Garden City BID Limited | Other services | 2017 |
| Welwyn Garden City Brewery Limited | Manufacturing | 2022 |
| Welwyn Garden City Builders Limited | Construction | 2013 |
| Welwyn Garden City Cleaners Ltd | Other services | 2021 |
| Welwyn Garden City Football & Social Club Limited | Arts & recreation | 2016 |
| Welwyn Garden City Golf Club Limited | Real estate | 1926 |
| Welwyn Garden City Group Limited | Extraterritorial | 2019 |
| Welwyn Garden City Locksmiths Limited | Construction | 2023 |
| Welwyn Garden City Plumbers Ltd | Extraterritorial | 2007 |
| Welwyn Garden City Plumbing and Heating Limited | Construction | 2008 |
| Welwyn Garden City Properties Limited | Real estate | 2018 |
| Welwyn Garden City Security Limited | Administrative & support | 2020 |
| Welwyn Hatfield Radio Ltd | Information & communication | 2021 |
| Welwyn Investment Ltd | Real estate | 2022 |
| Welwyn Partners Limited | Financial services | 2022 |
| Welwyn Plumbing and Heating Ltd | Construction | 2010 |
| Welwyn Pressive Ltd | Construction | 2016 |
| Welwyn Skip Hire Limited | Water & waste | 2021 |
| Welwyn Skips Ltd | Water & waste | 2020 |
| Welwyn Studios Ltd. | Administrative & support | 2009 |
| Welwyn Taxis Ltd | Transport & logistics | 2023 |
| Welwyn Tool Group Limited | Wholesale & retail | 2005 |
| Welwyn Traders Ltd | Wholesale & retail | 2023 |
| Welwyn Trading Ltd | Wholesale & retail | 2012 |
| Welwyn-Proved Installations Limited | Construction | 2010 |
| WELWYNA2BTAXIS Ltd | Transport & logistics | 2018 |
| Werling Scientific Limited | Professional & scientific | 2014 |
| WES One Limited | Construction | 2023 |
| West Wickham Playing Fields Trust Limited(The) | Arts & recreation | 1952 |
| Westgate Arches Ltd | Education | 2014 |
| Westside Welding and Engineering Limited | Wholesale & retail | 2003 |
| Weymouth Avenue (Dorchester) Limited | Professional & scientific | 1991 |
| WGC Green Garden Limited | Hospitality | 2025 |
| WGM Contracts Ltd | Information & communication | 2007 |
| Whalebones Properties Limited | Real estate | 2020 |
| Whanau Day Nursery (Welwyn GC) LLP | | 2013 |
| Wheatlands 24 Ltd | Real estate | 2019 |
| Whisky Signature Limited | Wholesale & retail | 2019 |
| Wholesome Fine Foods Ltd | Wholesale & retail | 2025 |
| Wideworld Limited | Construction | 2007 |
| Wilbos Ltd | Information & communication | 2018 |
| Wild Golf Ltd | Arts & recreation | 2025 |
| Wild Green Treecare Ltd | Administrative & support | 2025 |
| Wilkins Properties Herts Limited | Real estate | 2017 |
| Will Buy Your Property Ltd | Real estate | 2018 |
| Willow Events Limited | Administrative & support | 2005 |
| Willow Foundation | Other services | 2004 |
| Wills ACR Limited | Energy | 2025 |
| Wills Hvac Services Ireland Ltd | Construction | 2026 |
| Wills Hvac Services Limited | Manufacturing | 2013 |
| Wilmington Investments Limited | Real estate | 2001 |
| Wilmore Ltd | Real estate | 2021 |
| Wilson Holdings (London) Limited | Financial services | 2013 |
| Wilson Investments (London) Limited | Construction | 2017 |
| Wilson Properties (London) Ltd | Construction | 2000 |
| Wilson Residential Limited | Construction | 2016 |
| Winbasecloud Ltd | Wholesale & retail | 2024 |
| Windoorbase Trade Ltd | Construction | 2012 |
| Windover Development Limited | Construction | 2018 |
| Wings of Welwyn Limited | Wholesale & retail | 2012 |
| Wink Discoteque Ltd | Information & communication | 2012 |
| Wink Shop Direct Limited | Wholesale & retail | 2013 |
| Winners Support Care Limited | Health & social care | 2019 |
| Winslow Tandoori Ltd | Hospitality | 2021 |
| Wire Staffing Solutions Limited | Administrative & support | 2025 |
| Wise About Food Community Interest Company | Health & social care | 2019 |
| Wizardshield Ltd | Wholesale & retail | 2019 |
| WLG Catering Ltd | Hospitality | 2025 |
| Wojciech Lizut Ltd | Administrative & support | 2016 |
| Wonderland Child Care Limited | Administrative & support | 2008 |
| Wonderturn Limited | Other services | 1986 |
| Wooboom Ltd | Arts & recreation | 2016 |
| Woodberry Day Nursery (Fawley) Limited | Health & social care | 2019 |
| Woodberry Day Nursery (Peartree) Limited | Health & social care | 2008 |
| Woodberry Day Nursery (Sholing) Limited | Health & social care | 2015 |
| Woodberry Day Nursery (Waterlooville) Ltd | Health & social care | 2017 |
| Woodberry Day Nursery IP Limited | Administrative & support | 2019 |
| Woodhams Farm Day Nursery Limited | Education | 2007 |
| Woodlands Day Care Limited | Education | 2011 |
| Woodlands Developments Limited | Real estate | 2021 |
| Woodlands Retirement Village Limited | Administrative & support | 2012 |
| Woodman Chapmore Limited | Real estate | 2014 |
| Woodside Park Dental Limited | Health & social care | 2025 |
| Workforceflow AI Ltd | Information & communication | 2026 |
| WPL (WGC) Limited | Construction | 2016 |
| WPL Investments Limited | Construction | 2016 |
| WPL Investments NO.2 Limited | Construction | 2017 |
| WPL Residential Investments Limited | Real estate | 2017 |
| WPL Trading Limited | Financial services | 2018 |
| Write Spelling Limited | Information & communication | 2015 |
| Xandel Limited | Information & communication | 2010 |
| Xenon Automotive Ltd | Wholesale & retail | 2021 |