To meet a Regia Marina requirement for a two-seat catapult-launched seaplane, Piaggio produced two designs.

The first, designated the P.6bis, was a small biplane flying boat powered by a 190 kW (260 hp) Isotta Fraschini V.6 engine driving a pusher propeller.

Both aircraft had the same biplane wing structure with rigid strut bracing and both were armed with a single machine gun (the flying-boat's in the bow and the floatplane's in the rear cockpit).

In 1928, the P.6ter was produced based on the P.6 floatplane with the engine boosted to 306 kW (410 hp).

A production run of 15 P-6ter aircraft was produced for the Italian Navy where it had an unremarkable career, being used on battleships and cruisers.