| ACN Wellness Group Limited | Ashby De La Zouch | 2023 |
| ACO Electronics Limited | Royston | 1987 |
| ACO Recycling UK Limited | London | 2026 |
| ACO Technologies PLC | Shefford | 1984 |
| ACO247 Ltd | Bideford | 2023 |
| Acodent Limited | Bolton | 2014 |
| Acoia CYF | Pwllheli | 2021 |
| Acoloca Limited | Reading | 2004 |
| Acomb Engineering Limited | Hull | 2000 |
| Acoms Limited | Gravesend | 2008 |
| Acon Cutting Formes Limited | Oadby | 2005 |
| Aconda Industrial Carriers Limited | Witham | 2017 |
| Aconia Castings Limited | Birmingham | 1984 |
| Aconite Creations Ltd | Congleton | 2020 |
| Aconpex (UK) Limited | Leeds | 1990 |
| Acordis UK Limited | Cardiff | 1918 |
| Acorn (Hull) Limited | Hull | 2005 |
| Acorn Alarms Ltd | County Durham | 2007 |
| Acorn Aviation Ltd | Carrickfergus | 2024 |
| Acorn Bathrooms Limited | Leeds | 1989 |
| Acorn Bespoke Chilled Ltd | Purley | 2018 |
| Acorn Blinds NI Limited | Carrickfergus | 2014 |
| Acorn Bots Ltd | Harleston | 2018 |
| Acorn Brewery of Barnsley Limited | Barnsley | 2003 |
| Acorn Bridge Ltd | London | 2024 |
| Acorn Builders Ltd | Shipley | 2025 |
| Acorn Business Machines (Holmfirth) Ltd | Uxbridge | 2007 |
| Acorn Clearprint Limited | Newark | 2019 |
| Acorn Communications Systems Limited | | 1990 |
| Acorn Computers (Cambridge) Limited | Chippenham | 2009 |
| Acorn Conceptual Textiles Ltd | Nottingham | 2005 |
| Acorn Creative Print Ltd | Barnet | 2019 |
| Acorn Curtains and Blinds Ltd | Carlisle | 2018 |
| Acorn Door Systems Limited | Darwen | 2000 |
| Acorn Doors Glazing Ltd | Manchester | 2025 |
| Acorn Doors Ltd | Manchester | 2021 |
| Acorn Engineering (Holbeach) Limited | Spalding | 2005 |
| Acorn Engineering and Fabrications Ltd | Blaydon-On-Tyne | 2023 |
| Acorn Express Logistics Limited | Glasgow | 2004 |
| Acorn Fabrications Ltd | Darlington | 2016 |
| Acorn Furniture Sussex Limited | Newhaven | 2014 |
| Acorn Handling Limited | Mansfield | 1991 |
| Acorn Industrial Rubber Solutions Ltd | Wickford | 2016 |
| Acorn Interiors and Shopfitting Ltd | Salford | 2021 |
| Acorn Joinery and Kitchens Limited | Market Deeping | 2013 |
| Acorn Joinery Bath Ltd | Corsham | 2010 |
| Acorn Joinery Limited | New Milton | 2000 |
| Acorn Labels Limited | St. Ives | 1994 |
| Acorn Laser Limited | Washington | 1998 |
| Acorn Leisure NW Limited | Warrington | 2023 |
| Acorn Mobility Services Ltd. | Steeton Bradford | 1991 |
| Acorn Narrowboats Limited | Derby | 2023 |
| Acorn Office Accessories Limited | Coleford | 1982 |
| Acorn Packaging Supplies Limited | Walsall | 2003 |
| Acorn Plastech (UK) Limited | Cheltenham | 2005 |
| Acorn Plating Limited | Sandhurst | 1993 |
| Acorn Polymers (U.K.) Ltd | Bolton | 1998 |
| Acorn Powder Coating Limited | Bloxwich | 1981 |
| Acorn Press Swindon Limited | Cardiff | 1988 |
| Acorn Print (Southend) Ltd | Leigh-On-Sea | 2006 |
| Acorn Print Limited | Northwich | 2023 |
| Acorn Printing (Aberdeen) Ltd | Oldmeldrum | 2024 |
| Acorn Products Limited | Ruislip, | 2026 |
| Acorn Restorations Limited | Tredegar | 1995 |
| Acorn Saddlery Limited | London | 2003 |
| Acorn Screen Products Limited | Loughborough | 1988 |
| Acorn Seating Ltd | Kettering | 2019 |
| Acorn Signs & Engraving Limited | Mansfield | 1999 |
| Acorn Signs Limited | Inverness | 2001 |
| Acorn Sportswear Limited | Station Road | 1987 |
| Acorn Tank Services Ltd | Scarborough | 2012 |
| Acorn Target Systems Ltd | Lowestoft | 2002 |
| Acorn Thorn Ltd. | Quedgeley | 1995 |
| Acorn Timber Craft Ltd | Llanelli | 2023 |
| Acorn Timber Solutions Ltd | Doncaster | 2015 |
| Acorn Upholstery Limited | Gerrards Cross | 2008 |
| Acorn Web Offset Limited | Normanton Industrial Estate | 1987 |
| ACORN2OAK Innovation Solutions Limited | Warrington | 2008 |
| Acornceramics. Ltd | Reading | 2017 |
| Acornchain Limited | Stockton | 1992 |
| Acornco Ltd. | Bristol | 2002 |
| Acorns Coffee Roastery Ltd | Bordon | 2024 |
| Acoro Medical Limited | Leeds | 2023 |
| Acors Press Limited | Benfleet | 1996 |
| Acot Ltd | Beckenham | 2026 |
| Acota Limited | Birmingham | 2000 |
| Acousta Foam Limited | Dudley | 1980 |
| Acoustaproducts Limited | Bristol | 1991 |
| Acousteel Limited | Blaydon | 1999 |
| Acoustic Attenuations Ltd | Hove | 1992 |
| Acoustic Calibration Services Limited | Stevenage | 2001 |
| Acoustic Carpentry and Building Ltd | Bristol | 2022 |
| Acoustic Data Ltd | Edinburgh | 2017 |
| Acoustic Door Ltd | Brampton | 2013 |
| Acoustic Energy Loudspeakers Limited | Tetbury | 2017 |
| Acoustic Energy Ltd | Tetbury | 2022 |
| Acoustic Machines Limited | Liverpool | 2019 |
| Acoustic Monitoring International Ltd | Alton | 2023 |
| Acoustic Polymers Limited | Woking | 2006 |
| Acoustic Reproduction Technology Limited | Lanarkshire | 1998 |