Łomża Landscape Park of the Narew Valley (Polish: Łomżyński Park Krajobrazowy Doliny Narwi) is a protected area (Landscape Park) in north-eastern Poland, on the banks of the Narew river, close to the town of Łomża, to the south-east.
The protected area of the park consists of unique landscape features such as pristine valleys and marshes with high aesthetic appeal. The total area under protection amounts to 19,664 ha, of which 7,353.5 ha lies within the actual park boundaries, and the 12,310.5 ha creates park's protective buffer zone (Polish: otulina).
There are two nature reserves in the Park: Kalinowo and Wielki Dział.