| Lille Vinbar AS | Hospitality | 2025 |
| Lillehagen Fus Barnehage AS | Education | 2002 |
| Lillekrøll & Mutter'N AS | Wholesale & retail | 2025 |
| Lillestrøm Akvarium AS | Wholesale & retail | 1984 |
| Lillestrøm Arkitekter AS | Professional & scientific | 1994 |
| Lillestrøm Auto AS | Wholesale & retail | 2019 |
| Lillestrøm Bardrift AS | Hospitality | 2025 |
| Lillestrøm Bil & Rekvisita AS | Wholesale & retail | 1993 |
| Lillestrøm Bil Og Eiendom AS | Real estate | 2007 |
| Lillestrøm Bilsenter AS | Wholesale & retail | 2013 |
| Lillestrøm Bilservice AS | Other services | 2012 |
| Lillestrøm Bilvask Og Bilpleie AS | Other services | 2022 |
| Lillestrøm Bistro AS | Hospitality | 2019 |
| Lillestrøm Boliginvest AS | Hospitality | 2019 |
| Lillestrøm Boligutvikling AS | Real estate | 2019 |
| Lillestrøm Byutvikling AS | Real estate | 1999 |
| Lillestrøm Consult & Invest AS | Professional & scientific | 2017 |
| Lillestrøm Culture Hub AS | Education | 2021 |
| Lillestrøm Delta AS | Real estate | 2006 |
| Lillestrøm Eiendom AS | Real estate | 2017 |
| Lillestrøm Eiendomsmegling AS | Real estate | 2018 |
| Lillestrøm Eiendomsutvikling AS | Real estate | 2006 |
| Lillestrøm Event AS | Arts & recreation | 2019 |
| Lillestrøm Figur Helse Og Kost Salong AS | Other services | 2016 |
| Lillestrøm Glassvegg Ans | Manufacturing | 1995 |
| Lillestrøm Golfcenter Ans | Arts & recreation | 2001 |
| Lillestrøm Graving Og Transport AS | Construction | 2011 |
| Lillestrøm Gyn Klinikk AS | Health & social care | 1997 |
| Lillestrøm Kjøkkendesign AS | Wholesale & retail | 2019 |
| Lillestrøm Kjøkkenstudio AS | Wholesale & retail | 2019 |
| Lillestrøm Kjøtt Butikk AS | Wholesale & retail | 2020 |
| Lillestrøm Kulturbygg AS | Real estate | 2004 |
| Lillestrøm Kulturpub AS | Hospitality | 2006 |
| Lillestrøm Kvartal 6 AS | Real estate | 2020 |
| Lillestrøm Ladehub AS | Energy | 2025 |
| Lillestrøm Lungeklinikk AS | Health & social care | 2022 |
| Lillestrøm Muskel Og Leddklinikk AS | Health & social care | 2017 |
| Lillestrøm Oftalmologi AS | Health & social care | 2023 |
| Lillestrøm Optikk AS | Wholesale & retail | 2023 |
| Lillestrøm Parkering AS | Transport & logistics | 2003 |
| Lillestrøm Pølsevogn AS | Wholesale & retail | 2021 |
| Lillestrøm Regnskap Og Økonomi AS | Professional & scientific | 2014 |
| Lillestrøm Rørleggerbedrift AS | Construction | 1995 |
| Lillestrøm Skomakerverksted Ans | Other services | 1990 |
| Lillestrøm Tannhelse AS | Wholesale & retail | 2020 |
| Lillestrøm Tannklinikk & Tannlegevakt AS | Health & social care | 2014 |
| Lillestrøm Tannteknikk AS | Manufacturing | 1996 |
| Lillestrøm Utvikling AS | Real estate | 2013 |
| Lillestrøm Vest Holding AS | | 2026 |
| Lillestrøm VVS AS | Construction | 2017 |
| Lillestrøm Øyeklinikk AS | Health & social care | 2021 |
| Lillestrømeiendom AS | Real estate | 2022 |
| Lillestrømgynekologene AS | Health & social care | 2011 |
| Limwric AS | Professional & scientific | 2001 |
| Lin Øst AS | Real estate | 2006 |
| Lina - Pikene På Torvet AS | Hospitality | 2015 |
| Lindboms Gællby Bygg | Construction | 1997 |
| Lindemark Utbygging AS | Real estate | 2018 |
| Linderud Næring AS | Real estate | 2015 |
| Lindesteg Bo AS | Real estate | 2006 |
| Lindinvent AS | Wholesale & retail | 2024 |
| Linh Gård AS | Real estate | 2006 |
| Linns Krystallhule AS | Wholesale & retail | 2026 |
| Linntronics AS | Wholesale & retail | 2017 |
| Linorco Bygg AS | Construction | 2024 |
| LJ Consult AS | Professional & scientific | 2024 |
| Ljet AS | | 2019 |
| LLS Holding AS | | 2025 |
| Loadmaster AS | Transport & logistics | 2009 |
| Logent AS | Administrative & support | 2012 |
| Logent Produksjon AS | Professional & scientific | 2013 |
| Logent Warehousing AS | Transport & logistics | 2022 |
| Lokals Ventures AS | Real estate | 2018 |
| Lol AS | | 2021 |
| Lone Star Analysis AS | Information & communication | 2022 |
| Longjump AS | | 2023 |
| Lospes AS | | 2023 |
| Lovely Nails AS | Other services | 2021 |
| LS Pizza & Kebabhuset AS | Hospitality | 2023 |
| Ltown Invest AS | | 2019 |
| Ludo Nett Ans | Information & communication | 2003 |
| Ludwigsen Holding AS | | 2023 |
| Luméra Laser AS | Other services | 2025 |
| Lunde Transport Og Vaktmesterservice AS | Transport & logistics | 2018 |
| Lunsjbrakka Da | Hospitality | 2021 |
| Lupin Holding AS | | 2021 |
| Lutro AS | | 1976 |
| Lux Bilpleie AS | Other services | 2024 |
| Lux Drift AS | Hospitality | 2023 |
| Lux Hotel 1 AS | Real estate | 2024 |
| Lux Hotel 2 AS | Real estate | 2024 |
| Lux Næring AS | Hospitality | 2023 |
| Lux P-Hus AS | Transport & logistics | 2024 |
| Luxconsult AS | Wholesale & retail | 2022 |
| Luxury Cakes AS | Wholesale & retail | 2019 |
| LX Holding AS | | 2025 |
| Lyra Technologies AS | | 2026 |
| Lågen Og Øvre Glomma Kraftproduksjon AS | Energy | 2004 |
| Lærer'N Trafikkskole AS | Education | 2000 |
| Lærer'N Trafikkskole Lillestrøm AS | Education | 2020 |