The move expands IBM Clouds’ global footprint.
The facility is part of IBM’s $1.2bn investment in 2014 to expand its worldwide cloud footprint.
It enables customers to easily manage, run and store data and workloads in the country through less latency.
The data centre has capacity for about 11,000 servers and a power rating of 2.8 megawatts. It offers the entire range of IBM Cloud infrastructure services such as bare metal and virtual servers, storage, security, and networking.
SoftLayer chief technology officer Marc Jones said: "The Italian IT sector is changing as startups and enterprises alike are increasingly turning to the cloud to optimize infrastructure, lower IT costs, create new revenue streams, and spur innovation.
"The Milan data center extends the unique capabilities of our global platform by providing a fast, local onramp to the cloud. Customers have everything they need to quickly build out and test solutions that run the gamut from crunching big data to launching a mobile app globally."
The Milan facility joins existing SoftLayer EMEA cloud centres in London, Paris, Frankfurt and Amsterdam, enabling local customers to connect to SoftLayer services within Europe in less than 30 milliseconds.
Currently, there are over 40 IBM Cloud data centres globally, including 24 SoftLayer centres.