Ciechanowiec, back then just a fortified town, for the first time had been mentioned in the XIII century. The town was granted city rights by a Mazovian prince Janusz I the Great, probably at the beginning of the XV century. In 1434 the source mentions the Ciechanowian burgher for the first time, and since 1446 Ciechanowiec has its own Roman Catholic parish.

Since its founding till the beginning of the XX century Ciechanowiec had belonged to many families: Kiszkowie, Ciechanowieccy, Bremerowie, Jabłonowscy, Ossolińscy, Szczukowie, Ciecierscy and Starzeńscy. On account of its location Ciechanowiec was an important trade, road and defence centre. At the turn of the XV century one of the most important tracks from Mazowsze to Lithuania was leading through Ciechanowiec.

Ciechanowiec had been destroyed many times during: the Swedish Deluge (the Swedish invasion of Poland in 1655 – 1660), the II north war (1700 – 1721), the Polish-Russian war of 1792 and the Kościuszko’s Insurrection. After the third partition of Poland Ciechanowiec had been incorporated into the annexed territory under Prussian rule (1796 – 1806), and after the Napoleonic era Ciechanowiec had been permanently split into the left-bank Old Town and the right-bank New Town.

The development of Ciechanowiec had been quite successful during the Partitions period. Just before the outbreak of the World War I Ciechanowiec was inhabited by circa 15.000 residents. There were nearly 100 factories and around 300 trading points. During the World War I and the Polish-Soviet War of 1920, close to 65% of the city had been destroyed and the city’s population had dropped below 5000. Slow reconstruction of the war-damaged city got interrupted by an outbreak of the World War II. The double occupation of the city: Soviet in 1939 – 1941 and German in 1941 – 1944 resulted in further damage to Ciechanowiec. Nearly 85% of the city infrastructure was burned down and the population dropped to less than 2000 people.

After the liberation the first Municipal National Council had constituted itself on October 1944. The founding of the Trading – Grocery Partnership „Jedność” and the Municipal Co-educational Gymnasium were the most important actions of the Ciechanowiec’s people, taken even before the end of 1944. Among the buildings constructed in the following years are: an airfield (1951), the Municipal Hospital reconstructed in 1956, the pharmacy and the bakery (1963), the Firefighter’s House, the Book Store, the State Machines Centre (1966). Constructions of a dam on the Nurzec and a tourist centre Nurzec had also begun.

Above actions have not been left unnoticed. In 1966 Ciechanowiec was awarded with a nr 1 prize among the cities of Białostocczyzna with less than 5000 citizens. In 1971 it won the title of the Master of Thrift in its group, and in 1974 the title of the Grandmaster of Thrift. In 1975 the city have been awarded with the Commodore's Cross of the Order of Polonia Restituta.

As for the field of culture, an important fact is the forming of the Ciechanowiec Admirers’ Society in 1962, which led to founding of the main tourist attraction - the Rev. Krzysztof Kluk Museum of Agriculture in 1963.