| Whitehare Avenue Management Ltd | Households | 2024 |
| Whites Home Bakery Ltd | Manufacturing | 2019 |
| Whitethorn Lane Management Limited | Households | 2001 |
| Wild Creative Enterprises Ltd | Wholesale & retail | 2019 |
| Wilkham Roof Cleaning Services Ltd | Administrative & support | 2023 |
| William Patton Agricultural Contractor Ltd | Professional & scientific | 2012 |
| William Taggart Cars Limited | Wholesale & retail | 2022 |
| Willow Mews Management Ltd | Households | 2019 |
| Willowbrook Land Management Limited | Households | 2018 |
| Willowgrove Developments (N.I.) Ltd | Construction | 2016 |
| Wilson Marine Management Limited | Transport & logistics | 2024 |
| Wilsons Contractors NI Limited | Agriculture & fishing | 2020 |
| Wilyan Limited | Professional & scientific | 2018 |
| Window Films (N.I.) Limited | Construction | 1987 |
| Wishart Group (NI) Limited | Manufacturing | 2014 |
| WMC Enterprises Ltd | Construction | 2017 |
| Wolfpack Gym Equipment Ltd. | Wholesale & retail | 2020 |
| Women in Media Belfast CIC | Professional & scientific | 2024 |
| Wonder Products (NI) Limited | Wholesale & retail | 2011 |
| Woodburn Land Management Ltd | Real estate | 2003 |
| Woodlands Antrim Limited | Extraterritorial | 2012 |
| Woodside Global Limited | Transport & logistics | 1975 |
| Woodside Logistics Group Limited | Transport & logistics | 1978 |
| Woodside Motorfreight Limited | Transport & logistics | 1971 |
| Woodside Warehousing Limited | Transport & logistics | 1978 |
| Words of Truth Foundation Limited | Other services | 2002 |
| Wtjc Ltd | Arts & recreation | 2016 |
| Xeroplas Belfast Limited | Water & waste | 2019 |
| Yellow Jumper Productions Ltd | Administrative & support | 2024 |
| Youth Hubs | Information & communication | 2024 |