Kolno County (Polish: powiat kolneński) is a unit of territorial administration and local government (powiat) in Podlaskie Voivodeship, north-eastern Poland. It came into being on January 1, 1999, as a result of the Polish local government reforms passed in 1998. Its administrative seat and largest town is Kolno, which lies 89 kilometres (55 mi) west of the regional capital Białystok. The only other town in the county is Stawiski, lying 16 km (10 mi) east of Kolno.
The county covers an area of 939.73 square kilometres (362.8 sq mi). As of 2006 its total population is 39,676, out of which the population of Kolno is 10,751, that of Stawiski is 2,442, and the rural population is 26,483.