The figure had reached 17.5 percent by the end of 2015, Eurostat said, putting the country ahead of its target for 2020 five years early.
That was almost triple the figure of 6.3 percent in 2004.
Italy is one of 11 member states which has already reached its target, with Bulgaria, Croatia, the Czech Republic, Denmark, Estonia, Lithuania, Hungary, Romania, Finland, and Sweden also achieving the feat.
At the other end of the scale however, the Netherlands was furthest off reaching its 2020 target, followed by France, Ireland, the UK, and Luxembourg. That's despite the UK and Luxembourg having lower targets than countries like Italy.
The countries have been given different targets depending on factors such as population and natural resources.
Overall, Italy is in the middle of the pack when it comes to the proportion of its energy generated through renewable resources, placed 13th out of the 28 member states.
Every single town in the country can boast at least one source of renewable energy, with Italy a world leader in solar power in particular.
But one group which has unexpectedly benefited from the green energy boom is the mafia.
The poorer regions of Sardinia and Sicily were prime candidates for converting their warm climates into renewable energy, but in 2015, prosecutors warned of mafia infiltration in the sector - meaning the regions saw little of the profits made by energy firms.