| M.J. Eriksson A/S | 2635 | Ishøj |
| Madera aps | 7361 | Ejstrupholm |
| Malmos A/S | 4000 | Roskilde |
| Mariendal | 9000 | Aalborg |
| Marlon Tørmørtel A/S | 8740 | Brædstrup |
| Marmorline & Co. A/S | 7200 | Grindsted |
| Maskiner A/S | 8700 | Horsens |
| Maskinfabrikken Rational Aps | 2610 | Rødovre |
| Master Builders Solutions Denmark A/S | 6230 | Rødekro |
| Masytec A/S | 2605 | Brøndby |
| Max Weishaupt A/S | 2600 | Glostrup |
| Maycon A/S | 4700 | Næstved |
| Microsolutions A/S | 8700 | Horsens |
| Midtjydsk Beton-vare og Elementfabrik A/S | 7400 | Herning |
| Midtjysk Albyg A/S | 7490 | Aulum |
| Mirit Glas A/S | 2730 | Herlev |
| MLI Murerentreprise A/S | 8800 | Viborg |
| Mobilhouse A/S | 7000 | Fredericia |
| Modul-System HH A/S | 2605 | Brøndby |
| Mogens V. Zeltner A/S | 3520 | Farum |
| Molio | 2730 | Herlev |
| Molt Wengel Advokatpartnerselskab | 2100 | København Ø |
| Mul10 Metal A/S | 7130 | Juelsminde |
| Multi Montage Stoholm A/S | 7850 | Stoholm J |
| Multi-Services ApS | 7000 | Fredericia |
| MYHLENBERG BYG A/S | 9510 | Arden |
| MAXETA AS | 3660 | Stenløse |
| MedicSport A/S | 2750 | Ballerup |
| Midtgaard A/S | 4000 | Roskilde |
| MOE A/S | 2860 | Søborg |