| K F MAY Ltd | North Shields | 2023 |
| K J Crushing & Screening Ltd | Rhymney | 2015 |
| K J Property Investments Limited | Gwent | 2002 |
| K Lloyds Engineering Supplies and Services Limited | London | 2012 |
| K M Systems Facades Limited | London | 2014 |
| K P D Well Intervention Services Ltd | Birmingham | 2008 |
| K-Spection Ltd | Neston | 2018 |
| K. T. Montgomery Environmental Limited | Kilmarnock | 2014 |
| K.Cameron Ltd | Inverness | 2025 |
| K.D. Marine Limited | Inverurie | 1988 |
| K.F.M. Safety Co, Ltd | Liverpool | 2024 |
| K.G.B Rigging & Lifting Solutions Limited | Aberdeen | 2022 |
| K.P. & SON Ltd | Bridgend | 1999 |
| K.R. Applied Geology Ltd | London | 2017 |
| K1 Masonry Ltd | Glasgow | 2024 |
| K3DELTA Marine Aggregates Ltd | London | 2022 |
| K3NT Limited | Stirling | 1999 |
| Kabanga Nickel Limited | London | 2019 |
| Kabikah Ltd | London | 2024 |
| Kableyco Ltd. | Horsham | 2007 |
| Kabz Mining Import and Export Ltd | London | 2026 |
| Kadesss Limited | London | 2016 |
| Kadoma Mining PLC | London | 2023 |
| Kaflow Limited | Aberdeen | 2021 |
| Kairos Lithium Ltd | London | 2015 |
| Kairos Precious Metals Ltd | London | 2026 |
| KAL Tire (UK) Limited | Alfreton | 1977 |
| Kalahari Metals Limited | London | 2017 |
| Kali Ventures Ltd | London | 2025 |
| Kalizma Contracts Limited | London | 2018 |
| Kalm GAS Ltd | Enfield | 2024 |
| Kaloil Services Ltd | Aberdeen | 2015 |
| KAM Ropes Ltd | Aberdeen | 2025 |
| Kampac International PLC | Cardiff | 2008 |
| Kamri Ltd | Watford | 2018 |
| Kangjing Chemical Group UK Co., Limited | Beckenham | 2023 |
| KAP Trading Limited | London | 2025 |
| Kappa Solutions UK Ltd. | Chester | 1996 |
| Kappa Training & Consulting Services Limited | Chester | 2005 |
| Karapinar Energy Ltd | Bridport | 2020 |
| Karbure Logistik SA / Ltd | London | 2022 |
| Karen Agnes Design Limited | Dundee | 2014 |
| Kariba Resources Limited | Cardiff | 2012 |
| Karoo Power Ltd | London | 2019 |
| Kasch OIL and GAS Consultants Ltd | Stoke-On-Trent | 2010 |
| Kashton Group Limited | London | 2019 |
| Katalyst Data Management Limited | London | 2013 |
| Kateg Limited | Newry | 2015 |
| Kathari Energia Limited | Brierley Hill | 2021 |
| Katoro Refinery Limited | Ashbourne | 2023 |
| Kavango Resources PLC | London | 2017 |
| Kayode HG Limited | London | 2007 |
| Kazopp Limited | Yeovil | 2014 |
| KB Rope Access Pipe Fitter Limited | Tranent | 2026 |
| KB Umbilical Services Ltd | Aberdeen | 2023 |
| KBK Holdings Ltd | London | 2025 |
| KBM Contracts Limited | Isle Of Lewis | 2018 |
| KBM Inspection Services Ltd | Peterhead | 2014 |
| Kbsf Drilling Ltd | London | 2012 |
| KCA Deutag (Land RIG) Limited | Leeds | 2005 |
| KCA Deutag Alpha Limited | Leeds | 2007 |
| KCA Deutag Caspian Limited | Leeds | 1985 |
| KCA Deutag Drilling Group Limited | Leeds | 1972 |
| KCA Deutag Enterprises Limited | Leeds | 2008 |
| KCA Deutag Limited | Portlethen | 2008 |
| KCA Deutag RIG Design Services Limited | Portlethen | 2012 |
| KCA Deutag Technical Support Limited | Portlethen | 2001 |
| KCB Investment Group Ltd | London | 2022 |
| KCG Consultants Limited | East Grinstead | 1999 |
| KD Mining Company (UK) Limited | London | 2017 |
| KD Plant and Haulage Ltd | Burnley | 2021 |
| KDM Subsea Solutions Ltd | Aberdeen | 2025 |
| KDR Access Ltd | Musselburgh | 2013 |
| KEA Mineral Services Ltd | Truro | 2015 |
| Keady Quarry Ltd | Coleraine | 2014 |
| Kearton Crushing and Screening Limited | Co Durham | 2006 |
| Keates Quarries Limited | Swanage | 2012 |
| Keaytech Ltd | Newtown | 2020 |
| Kedougou Gold Limited | Cheltenham | 2017 |
| Keen 2 Screen Ltd | Omagh | 2020 |
| Keenaghan Aggregates Limited | Omagh | 2013 |
| Kefi Minerals (Ethiopia) Limited | London | 1997 |
| Keilloh Oilfield Services Limited | Aberdeen | 2026 |
| Keith Clark Technical Services Limited | | 2007 |
| Keith Mitchell Lifting Limited | Alford | 2021 |
| Kelert Limited | Caernarfon | 2008 |
| Kellas Cats Limited | London | 2012 |
| Kellogg Brown & Root Solutions Limited | Leatherhead | 1986 |
| Kelly Mitchell Automotive Ltd | Falkirk | 2012 |
| Kellys Sand and Gravel Limited | Strabane | 2012 |
| Kelpies Properties Ltd | Falkirk | 2019 |
| Kemro GEO Mining Ltd | Preston | 2019 |
| Kendrick Resources PLC | South Kensington | 1989 |
| Keng Offshore Engineering Limited | Aberdeen | 2018 |
| Kennel Minerals Limited | Harrogate | 2012 |
| Kennet OIL Logistics Limited | Wadebridge | 2007 |
| Kenneth Sinclair E&I Ltd | Auchterarder | 2016 |
| Kenny D Consultant Ltd | Chalfont St. Giles | 2025 |
| Kensel Smith Limited | Edinburgh | 2019 |
| Kenway Electrical Ltd | Inverness | 2016 |