| A Jarvis Electrical (Widnes) Limited | Chester | 2016 |
| A Jenkins Ltd | Ely | 2020 |
| A Jennings Building Contractors Ltd | Grange-Over-Sands | 2018 |
| A Jepson Electrical Ltd | Clitheroe | 2011 |
| A Jewell GAS Engineer Ltd | Biggleswade | 2019 |
| A JOB Well Done Plumbing and Heating Engineers Limited | Eastbourne | 2009 |
| A Jobe Construction Limited | Newquay | 2012 |
| A Joel Roofing Ltd | Dunstable | 2023 |
| A John Plumbing & Heating Limited | Goodwick | 2018 |
| A Johnson Brickwork Ltd | Spalding | 2021 |
| A Johnson Building Services Ltd | Wallsend | 2026 |
| A Johnson Heating and Plumbing Ltd | Evesham | 2022 |
| A Jones & Sons Limited | Blackburn | 2023 |
| A Jones Brickwork Limited | Peterborough | 2022 |
| A Jones Civil Engineering Limited | Gwynedd | 2013 |
| A Jones Contractors Ltd | Guildford | 2018 |
| A Jones Drylining Limited | Bilston | 2015 |
| A Jones Electrical Engineering Limited | Stockton-On-Tees | 2014 |
| A Jones Electrical Limited | Chelmsford | 2016 |
| A Jones Electrics Ltd | Wirral | 2019 |
| A Jones General Building & Maintenance Limited | Brecon | 2015 |
| A Jones Plumbing & Heating Limited | Sandown | 2024 |
| A Jones Property Solutions Ltd | Sittingbourne | 2023 |
| A Jones Roofing Contractors Limited | Manchester | 2017 |
| A Josan Builders Ltd | Slough | 2026 |
| A Joyful Consultancy Ltd | Kington | 2024 |
| A Jude Heating and Plumbing Ltd | Liverpool | 2021 |
| A Jutzeler (U.K.) Limited | Rushden | 1987 |
| A K Windows Limited | Wolverhampton | 2009 |
| A K @ Construction & Maintenance Ltd | Malvern | 2013 |
| A K a Brickwork Contractors Limited | Bristol | 2008 |
| A K Aspires Ltd | Grays | 2024 |
| A K Assistance Limited | London | 1995 |
| A K Automation and Control Limited | Portsmouth | 2002 |
| A K Bishop Building Services Ltd | Chorley | 2017 |
| A K Brickwork Contractors Ltd | London | 2021 |
| A K Builders & Plumbers Ltd | Chatteris | 2017 |
| A K Builders Limited | Harrow | 2008 |
| A K Building & Decorating Ltd | Manchester | 2014 |
| A K Building Services Limited | Hessle | 2003 |
| A K Building Solutions (Yorkshire) Ltd | Bradford | 2018 |
| A K Carpentry Services Ltd | Leighton Buzzard | 2003 |
| A K Chant Ltd | Chard | 2005 |
| A K Communications Limited | Alcester | 2014 |
| A K Concept Ltd | London | 2025 |
| A K Controls Ltd | Poole | 2003 |
| A K Cooling Ltd | London | 2020 |
| A K D Electrical Limited | Battlesbridge | 2012 |
| A K D Fire & Security Ltd | Kendal | 2002 |
| A K Deco Limited | Watford | 2023 |
| A K Development (Bristol) Ltd | Bristol | 2014 |
| A K Developments Anglesey Ltd | Pentraeth | 2002 |
| A K Doors and Gates Limited | East Grinstead | 2010 |
| A K Electrical Contractors Limited | Dorking | 1999 |
| A K Electrics Limited | Hampton | 2011 |
| A K Flooring Ltd | West Midlands | 2002 |
| A K Flooring Solutions Ltd | Runcorn | 2019 |
| A K G Davies (Dri-Lining) Limited | Hereford | 2003 |
| A K G Fencing Services Limited | Cosham | 2003 |
| A K GAS and Heating Services Limited | Hayes | 2010 |
| A K Hobson Limited | Essex | 2000 |
| A K Holdings London Limited | Ilford | 2021 |
| A K Home Improvements Ltd | Bedford | 2021 |
| A K Home Solutions Limited | Coventry | 2024 |
| A K John General Building & Maintenance Ltd | Manchester | 2025 |
| A K Kilgarriff Limited | Euxton Lane, Chorley | 2015 |
| A K Kitchen & Bedroom Ltd | Northolt | 2021 |
| A K Kitchens & Bathrooms (Wolverhampton) Ltd | Wolverhampton | 2014 |
| A K Lane & SON Ltd | Huntingdon | 2013 |
| A K Lippett Plumbing & Heating Limited | Redhill | 2016 |
| A K M Homes Limited | Liverpool | 2018 |
| A K Multi-Trades Ltd | London | 2024 |
| A K P Building Services Limited | Scarborough | 2017 |
| A K P Scotland Limited | East Kilbride | 1990 |
| A K Painting Services Ltd | Staines-Upon-Thames | 2015 |
| A K Plumbers and Joiners Limited | Shipley | 2013 |
| A K Property and Landscaping Ltd | Poole | 2022 |
| A K Roofing & Guttering Limited | Surrey | 2003 |
| A K S Electrical (Kent) Ltd. | Sittingbourne | 2007 |
| A K Scaffold Limited | Derry | 2019 |
| A K Scaffolding Services Limited | Bristol | 2019 |
| A K Timber Systems Limited | Liverpool | 2012 |
| A K Todd Builders Limited | Grimsby | 2013 |
| A K Udegbunam Resources Ltd | Edgware | 2018 |
| A K W Building Services Limited | Bristol | 2000 |
| A K W Holdings Limited | Warwickshire | 2017 |
| A K Warren Building Services Limited | Horsham | 2021 |
| A K Wilson Roofing Ltd | Dalry | 2026 |
| A Kane Contracts Ltd | Ballymoney | 2022 |
| A Karch Roofing Limited | Wakefield | 2009 |
| A Kattan Ltd | Southall | 2026 |
| A KAY Access Limited | Middlesbrough | 2025 |
| A Kelly Plastering Limited | Liverpool | 2014 |
| A Kelsey Construction Limited | Atherstone | 2018 |
| A Kendall Fireplace Fitters Ltd | Leigh | 2013 |
| A Kendall Limited | Oswestry | 2014 |
| A Kennerley T/A KPS Ltd | Congleton | 2025 |
| A Keys Construction Ltd | Richmond | 2021 |
| A Kilian Services Ltd | Brentwood | 2011 |
| A Kimber Carpentry Limited | Oxfordshire | 2004 |