| CSIT S.p.A. | Rome |
| CSM Sistemi S.r.l. | Varese |
| CSR Computer System | Rimini |
| CTA Informatica S.r.l. | Como |
| CTE Matera | Matera |
| Cubbit S.r.l. | |
| Cube Comunicazione S.r.l. | Bari |
| Cube Labs | Rome |
| Cube S.r.l. | Genoa |
| Cubic Design | Lucca |
| Cuordimela S.r.l. | Milan |
| Custom Engineering S.p.A. | Parma |
| CY4GATE S.p.A. | |
| Cyber Dyne S.r.l. | |
| Cyber Trade S.r.l. | Ravenna |
| Cyber Xcelerator | Rome |
| Cyberangels S.r.l. | |
| Cyberg | Bergamo |
| CyberPlan | Friuli-Venezia Giulia |
| Cybion | Rome |
| CyLock S.r.l. | |
| Cynasky Web Multimedia | Rome |
| CyNexo S.r.l. | |
| Cytosens | Milan |
| D e D Automazione Industriale | Milan |
| D-Orbit S.p.A. | |
| D.A.Tel S.n.c. | Florence |
| D.B.L. Di Benedetto Luigi & C. S.a.s. | Friuli-Venezia Giulia |
| D.B.R. S.r.l. | Vicenza |
| D4RE | Milan |
| Dacuna Studio | Brescia |
| Dagomedia S.r.l. | Ancona |
| Daisoft | Pesaro and Urbino |
| Dam Sistemi S.r.l. | Reggio Emilia |
| Damedia | Avellino |
| Daniele Martini | Pistoia |
| DaniSoft S.r.l. | Brescia |
| DAo Studio S.r.l. | |
| Darwin Computing | Turin |
| Data Appeal Company S.p.A. | |
| Data Job | Venice |
| Data Masters S.r.l. | |
| Data Proget S.r.l. | Arezzo |
| Data Recovery Service Italia | Milan |
| Data Rescue Italia | Milan |
| Data Science Milan | Milan |
| Datacode S.r.l. | Modena |
| Datacom | Livorno |
| Datadisc.it S.r.l. | Syracuse |
| Datagest S.r.l. | Pesaro and Urbino |