No. A Polish national identity card (dowód osobisty) is not valid for entry into Italy. Polish citizens must present a valid passport.
Reason: While both Poland and Italy are EU and Schengen members, Italy has not fully implemented the EU regulation allowing ID-card-only entry for all EU citizens in every context. In practice, Italian border authorities require a passport for non-EU/Schengen flights and may refuse ID cards at air borders due to document-verification standards. A passport is universally accepted and avoids any risk of denied boarding or entry.
Exception: Polish citizens traveling by land from another Schengen country (e.g., driving from Austria or Slovenia) may use an ID card for border crossing, but airlines will still demand a passport for check-in.
Recommendation: Always carry a passport when flying to Italy.