| J. E. Pedersen Maskinfabrik A/S | 4600 | Køge |
| J. Langkjær Stålbyg A/S | 7480 | Vildbjerg |
| J.P.J. Træemballage ApS | 9560 | Hadsund |
| JAI Overfladebehandling A/S | 7480 | Vildbjerg |
| Jakob Albertsen A/S | 5700 | Svendborg |
| Jakobsen Planslibere ApS | 7100 | Vejle |
| JB Production A/S | 8700 | Horsens |
| JBR Consult | 8800 | Viborg |
| JCV MachineTools ApS | 6000 | Kolding |
| Jens Linde A/S | 7100 | Vejle |
| Jens S Transmissioner A/S | 2630 | Taastrup |
| JENSEN Denmark A/S | 3700 | Rønne |
| Jensen Metal A/S | 8361 | Hasselager |
| Jensen Metal A/S | 8361 | Hasselager |
| JensT ApS | 4100 | Ringsted |
| Jinan Bodor CNC Machine Co.,Ltd | 250000 | Jinan, Shandong |
| JJ Mechatronic A/S | 4450 | Jyderup |
| JKS | 8700 | Horsens |
| JLM teknik ApS | 9500 | Hobro |
| JMS Danmark ApS | 5000 | Odense C |
| JNF Momentum A/S | 4600 | Køge |
| Job i Fokus | 2200 | København N |
| JobTeam A/S | 6700 | Esbjerg |
| John Bjerrum Nielsen A/S | 6740 | Bramming |
| John Crane Danmark | 3650 | Ølstykke |
| Johnson Metal A/S | 2630 | Tåstrup |
| Jotun Danmark A/S | 6000 | Kolding |
| jpbc A/S | 8840 | Rødkærsbro |
| Jubo Rustfrit Stål A/S | 8362 | Hørning |
| JUMBO Stillads A/S | 6000 | Kolding |
| Junget A/S | 8382 | Hinnerup |
| JW Industri A/S | 7430 | Ikast |
| Jymika A/S | 8723 | Løsning |
| Jysk Kranservice ApS | 9240 | Nibe |
| Jysk Pension | 9200 | Aalborg SV |
| Jørgensen & Utoft A/S | 7100 | Vejle |