| Hyronspear Property Company Limited | Real estate | 1973 |
| I W Technical Solutions Ltd | Other services | 2007 |
| IAN Brumpton Plumbing & Heating Services Limited | Construction | 2017 |
| IAN Moore Contracting Ltd | Administrative & support | 2024 |
| IAN Short Developments Limited | Construction | 2021 |
| Ideal Lincs Limited | Wholesale & retail | 2005 |
| Igneous Designs Limited | Wholesale & retail | 2020 |
| Impact Padel Lincoln Ltd | Arts & recreation | 2025 |
| Incubation Experts Ltd | Wholesale & retail | 2013 |
| IND Parts Limited | Wholesale & retail | 2014 |
| Indalo Solutions Ltd | Other services | 2019 |
| Indian Curry POT Limited | Hospitality | 2024 |
| Indigo Ebony Willmington Ltd | Extraterritorial | 2024 |
| Innovation Works (Lincs.) Ltd | Real estate | 2012 |
| Inspire Counselling Ltd | Health & social care | 2021 |
| Interlect Electrical Services Limited | Construction | 2004 |
| Internet Software Technology Limited | Information & communication | 2008 |
| Intuition Group Ltd | Construction | 2025 |
| Inventive Solutions Tech Limited | Information & communication | 2020 |
| Inviva Digital Healthcare Limited | Professional & scientific | 2025 |
| Inviva Healthcare Management Limited | Professional & scientific | 2023 |
| Invoice Finance Solutions Limited | Financial services | 2002 |
| Ipds Group Limited | Construction | 2012 |
| Isoinox Ltd | Manufacturing | 2024 |
| ITS Training (UK) Ltd. | Professional & scientific | 2001 |
| J Bradley Electrical Limited | Construction | 2003 |
| J C Stocks Construction Ltd | Construction | 2019 |
| J D B Mini Plant Limited | Construction | 2023 |
| J E Cheer Farming Ltd | Agriculture & fishing | 2016 |
| J E Dale (Farmers) Limited | Agriculture & fishing | 2002 |
| J E Marshall Property Services Limited | Real estate | 2017 |
| J F Machinery Limited | Wholesale & retail | 2025 |
| J H Bulman Consultancy Ltd | Education | 2015 |
| J P Home Improvements Lincs Limited Liability Partnership | | 2022 |
| J P Stuart Ltd | Construction | 2014 |
| J R Glenn & Daughters Limited | Wholesale & retail | 2012 |
| J S & J Buckley Limited | Agriculture & fishing | 2020 |
| J Sharp Education Ltd | Education | 2026 |
| J T Food Cre-Ateur Limited | Hospitality | 2009 |
| J Thompson Inspection Ltd | Professional & scientific | 2013 |
| J&H Liquidations Ltd | Wholesale & retail | 2025 |
| J. Neave (Saxby) Limited | Agriculture & fishing | 1976 |
| J. Ward Farming | Agriculture & fishing | 1959 |
| J.G.Dring & SON Limited | Agriculture & fishing | 1955 |
| J.O.C Limited | Other services | 2017 |
| Jackjumper Ltd | Manufacturing | 2021 |
| Jackson Commercials Ltd | Wholesale & retail | 2024 |
| Jackson Events Ltd | Information & communication | 2026 |
| JAD Associates (Improvement Solutions) Limited | Professional & scientific | 2006 |
| Jam-Jar Developments Ltd | Construction | 2023 |
| James D Wood Limited | Wholesale & retail | 2026 |
| Jarralad Ltd | Professional & scientific | 2024 |
| JAS Mechanical Limited | Extraterritorial | 2024 |
| Jasper E Bars Ltd | Wholesale & retail | 2022 |
| JC Protech Limited | Construction | 2024 |
| JCF & RJF Limited | Health & social care | 2014 |
| Jcjt Limited | Real estate | 2023 |
| JCS Joinery and Construction Services Limited | Construction | 2007 |
| JD Electrical Lincoln Ltd | Construction | 2020 |
| Jdzill Ltd | Construction | 2017 |
| Jessie's Farm Shop Limited | Wholesale & retail | 2012 |
| JEX Pumping Limited | Professional & scientific | 2015 |
| JHH Ltd | Professional & scientific | 2021 |
| Jihana Belle Daisy Slavin Disley Ltd | Extraterritorial | 2024 |
| JJ Couriers (Lincs) Ltd | Transport & logistics | 2025 |
| Jjeenergy Limited | Construction | 2017 |
| JKL Consultancy Services Ltd | Professional & scientific | 2017 |
| Jlttransport Ltd | Transport & logistics | 2017 |
| JO Kelly Upholstery Ltd | Wholesale & retail | 2025 |
| Joe's Toes Ltd | Manufacturing | 2021 |
| John Booth & Sons (Lincoln) Limited | Agriculture & fishing | 1984 |
| Jonathan West Limited | Real estate | 2012 |
| Jones Cladding Solutions Limited | Construction | 2025 |
| Joseph Lake Building Conservation Ltd | Construction | 2025 |
| Josteph Limited | Other services | 2019 |
| Jowfix Autos Ltd | Wholesale & retail | 2024 |
| JPG Electrical Limited | Construction | 2019 |
| JPO Coatings Ltd | Wholesale & retail | 2020 |
| JPO Connect Limited | Professional & scientific | 2023 |
| JR & ZE Wold Barns Limited | Extraterritorial | 2016 |
| JRA CAM Limited | Professional & scientific | 2022 |
| JRH Water Management Limited | Water & waste | 2014 |
| JSB Sourcing Ltd | Wholesale & retail | 2023 |
| Jubu Spice Ltd | Hospitality | 2025 |
| Junel Store ARE Ltd | Wholesale & retail | 2025 |
| JW Lincolnshire Limited | Extraterritorial | 2008 |
| Jwwsolutions Ltd | Wholesale & retail | 2025 |
| K C Heating (Market Rasen) Limited | Construction | 2003 |
| K. B. Investment Holdings Ltd | Real estate | 2018 |
| K. B. Property Holdings Ltd | Real estate | 2018 |
| K. B. Salmon (Building & Joinery) Limited | Construction | 2005 |
| K.R. & S.R. Spilman | Agriculture & fishing | 1994 |
| K9 Athletics Ltd | Wholesale & retail | 2023 |
| Kaleidoscope Care Limited | Health & social care | 2011 |
| Karl Graham (Joinery) Limited | Construction | 2003 |
| KAT Agricultural Services Ltd | Agriculture & fishing | 2024 |
| KAY V. Strawson & Co Ltd | Professional & scientific | 2002 |
| Kcaccounts Limited | Professional & scientific | 2014 |
| Kenway Nurseries Limited | Wholesale & retail | 2010 |
| Kirkham Holdings Limited | Financial services | 2017 |