The Po Valley, Po Plain, Plain of the Po, or Padan Plain (Italian: Pianura Padana or Val Padana) is a major geographical feature of Italy. It extends approximately 650 km (400 mi) in an east-west direction, with an area of 46,000 km² (17,756 mi²) including its Venetic extension not actually related to the Po River basin; it runs from the Western Alps to the Adriatic Sea. The flatlands of Veneto and Friuli are often considered apart since they do not drain into the Po, but they effectively combine into an unbroken plain.

The plain is the surface of an in-filled system of ancient canyons (the "Apennine Foredeep") extending from the Apennines in the south to the Alps in the north, including the northern Adriatic. In addition to the Po and its affluents the contemporary surface may include the Savio, Lamone and Reno to the south; the Adige, Brenta, Piave and Tagliamento to the north, which are part of Venetian Plain. among the many streams that empty into the north Adriatic from the west and north.