| Keomin Solutions Ltd | Coleraine | 2025 |
| Keondi Mining Limited | Edinburgh | 2020 |
| Kernow Geoscience Limited | Oxford | 2018 |
| Kernow Mining Optimisation - Fleet Ltd | Redruth | 2022 |
| Kerume Services Limited | Edinburgh | 2025 |
| Kessington Engineering Ltd | Glasgow | 2015 |
| Kestrel Energy Solutions Ltd | Thames Ditton | 2018 |
| Ketford Limited | Bangor | 2010 |
| KEW Soda Ltd | London | 2016 |
| Key Empire Resources (UK) Limited | Mitcham | 2011 |
| Key Metals Group Ltd | London | 2022 |
| Keys Productions I Ltd | London | 2018 |
| KG Electrical Design Ltd | Aberdeen | 2011 |
| KG Offshore Limited | Norwich | 2019 |
| KG1 Dundee Ltd | Dundee | 2024 |
| KGJ Access Limited | Sowerby Bridge | 2019 |
| KGL OIL and GAS Engineering Limited | Aberdeen | 2021 |
| Khaimat LLC Ltd | Stoke In Stoke | 2022 |
| Kibali (UK) Limited | London | 2025 |
| Kieran Cameron Ltd | Aberdeen | 2021 |
| Kilbride Resources Limited | Edinburgh | 2007 |
| Kilbroney Plant Ltd | Newry | 2018 |
| Kilrymont Geoscience Limited | | 2005 |
| Kilvington Grove Limited | Newcastle Upon Tyne | 2018 |
| Kilwaughter Minerals Limited | Kilwaughter | 1939 |
| Kimberley Solutions Limited | Aberdeenshire | 2005 |
| Kims Mining Company Limited | London | 2026 |
| Kincorth Enterprises Limited | Aberdeen | 2013 |
| Kinegar Quarries Limited | Glasgow | 2006 |
| King Bros Quarry Ltd | Armagh | 2016 |
| Kingfisher Geological Services Ltd | Scarborough | 2017 |
| Kintyre Logistix Ltd | Campbeltown | 2017 |
| Kipinat Limited | Bedford | 2023 |
| Kirkmyres Sand & Gravel Limited | Fraserburgh | 1982 |
| Kirkton Engineering Limited | Stonehaven | 2017 |
| Kirktown Engineering Ltd. | Stonehaven | 2010 |
| Kistos Energy Africa Limited | London | 2026 |
| Kistos Energy Middle East Limited | London | 2025 |
| Kitaa Mining Ltd | London | 2024 |
| Kizi Limited | Weybridge | 2021 |
| KJ Access Limited | Middlesbrough | 2019 |
| KJA Well Services Ltd. | Angus | 2000 |
| KJM Inspection Services Ltd | Falkland | 2017 |
| KJR Well Services Limited | Montrose | 2016 |
| KKC Limited | Maud | 2006 |
| KKM Engineering Limited | Carnoustie | 2011 |
| KLM Consulting Solutions Limited | Falkirk | 2020 |
| KLX Holdings Limited | London | 2026 |
| KM Services (Grampian) Limited | Aberdeen | 2008 |
| KMA Contractors Ltd | Montrose | 2015 |
| Kmac Oilfield Solutions Limited | Torphins | 2001 |
| KMM Offshore Services Ltd | Kirriemuir | 2019 |
| KMO Services Ltd | Buckie | 2022 |
| Knighton Sandpit Limited | Totland Bay | 1968 |
| Knights Bay Oryx Ltd | Folkestone | 2022 |
| Knights of Engineering Ltd | Guildford | 2017 |
| Knowing Earth Limited | Bristol | 2017 |
| Knox Maritime Ltd | Aberdeen | 2024 |
| KNW Access Solutions Ltd | Dalton-In-Furness | 2025 |
| KOB Controls Limited | South Shields | 2015 |
| Kobald Mining Services Limited | Southport | 2015 |
| Kobold Metals UK Limited | London | 2024 |
| Kodal Lithium Exploration Limited | London | 2026 |
| Kodal Minerals PLC | London | 2010 |
| Kodal Mining UK Limited | London | 2022 |
| Kodal Norway (UK) Limited | London | 2013 |
| Koigeos Limited | London | 2023 |
| Kongo Potash Limited | East Grinstead | 2025 |
| Kopervik Plant Nutrition International Ltd | Blackfriars, London | 2025 |
| Kore Potash PLC | London | 2017 |
| Kosmos Energy Ghana Holdings Limited | London | 2021 |
| Kosmos Energy Investments Senegal Limited | London | 2016 |
| Kosmos Energy LNG Marketing Ltd | London | 2022 |
| Kotlien Ltd | Birmingham | 2025 |
| Kottes [KOT Training & Education Services] Limited | Nottingham | 2017 |
| Koza Ltd. | London | 2014 |
| KP Mahamanou OIL & GAS Limited | Peterborough | 2024 |
| KP Offshore Ltd | Great Yarmouth | 2019 |
| KP Rope Access Limited | Jarrow | 2026 |
| KPJ Projects Ltd | Arbroath | 2026 |
| KPM Consulting Service Limited | Leamington Spa | 2015 |
| KPS Engineering Services Ltd | Glasgow | 2018 |
| KR Integrity Services Ltd | Hebburn | 2021 |
| KR Quality Ltd | Stonehaven | 2026 |
| KR Tubular Inspection Services Ltd | Montrose | 2022 |
| Kraaivlei Konsulting Ltd | Wallingford | 2021 |
| Kraken Subsea Limited | Aberdeen | 2019 |
| Krea Engineering Limited | Stonehaven | 2008 |
| Kropz PLC | Hitchin | 2018 |
| KRR Construction Ltd | Choppington | 2019 |
| KSN Asset & Project Support Ltd | Saltcoats | 2025 |
| KT Access Limited | Kilsyth | 2008 |
| KT Drilling Consultants Limited | Cheltenham | 1998 |
| Kubez Ltd | Holt | 2020 |
| Kudu Resources Limited | London | 2022 |
| Kufpec UK Limited | London | 2010 |
| Kurek Marine Limited | Horbury | 2020 |
| Kutsal Trading Ltd | London | 2025 |
| KW - OIL & GAS 1 Limited | Edinburgh | 2025 |
| Kwama Mondial Group (UK) Limited | Woking | 2021 |