Markit/ADACI's services purchasing managers' index (PMI) for Italy increased to 53.8 in February from 53.6 in January.
A reading above 50 indicates expansion in the sector.
The index was driven by a faster growth in new business.
"The service sector maintained growth momentum into February, with businesses recording higher levels of activity as well as a faster rise in incoming new work," an economist at Markit Phil Smith said.