In June 1940 the Regia Marina, as it did with its battleships, entered the war with a fleet of completely renovated cruisers. There were still the old San Giorgio, Bari and Taranto (ex Pillau , and ex Strassburg received from the Germans after WW I), but all other units were of the kinds contemplated by the Treaty of Washington. The heavy cruisers had a displacement of 10,000 tons and were armed with guns up to 203 mm (8in); light cruisers had a displacement ranging from 5000 to 9000 tons and guns up to 152 mm (6in).

The light cruisers included four different types, the so called "5000" of the Condottieri class, the "7000" of the Montecuccoli class, the "8000" of the Eugenio di Savoia class to end with the "9000" of the Garibaldi class. During the construction of the first "5000", the four Di Giussano, Da Barbiano, Colleoni and Bande Nere, as with the Trento, focus was almost exclusively given to speed. Therefore, these units had power plant of 95,000 HP similar to the 10,000 ton Zara class, which propelled these units up to 37 knots. Consequently, armor was very light with only 20-24 mm, completely inadequate to protect the vital organs of the ship against guns of 152 mm of which they were armed. Furthermore, due to the absence of underwater protection, all four units were sunk by enemy attack by means of torpedoes.

The "7,000" of the Montecuccoli class represented an improvement over the "5000", but shared the same structural deficiencies with the Attendolo loosing its bow to a torpedo attack , and then being sunk in Naples by aerial bombardment. Definitely improved were the subsequent Duca d'Aosta and Eugenio di Savoia and finally the two Garibaldi and Duca degli Abruzzi which represented the completion of the evolution of the Italian light cruiser reaching 10,000 tons and an armament of 10 152mm guns while all other units had only 8. Both heavy and light cruisers were equipped with torpedoes at exemption of the Zara class. The light cruisers of the Condottieri class had 4 double launchers in trainable installations placed on deck near the stern smokestack. Similar layout was present on the Montecuccoli class, but with the launchers placed slighter more forward, at about half way between the two smokestacks.

The Duca d'Aosta and the Garibaldi had instead only 6 launchers in two triple-complexes, placed in the same location on deck. The catapults for airplanes on Di Giussano class were fixed and place on the most forward part of the bow. Instead, the Cadorna, Montecuccoli and the Duca d'Aosta had movable catapults placed between or behind the smokestacks. Finally, the Garibaldi had two catapults placed behind the stern smoke stack.

During the war, the Regia Marina laid down 12 light cruisers of the Attilio Regolo (or Capitani Romani) class, but by September 8, 1943 only three, Attilio Regolo, Pompeo Magno and Scipione Africano had entered service. The remaining units were either scraped or captured by the Germans.

Two anti-aircraft cruisers, the Etna and the Vesuvio were built transforming two units ordered by Siam from the Cantieri Riuniti dell'Adriatico, but never entered service. During the war, the Regia Marina incorporated two French cruisers captured in Toulon, the FR 11, Jean De Vienne, and the FR 12, La Galissonlère but they never entered service.