[1] The earliest known mention of Radziejów is found in a document from 1142, which states that it was given by the High Duchess consort of Poland Salomea of Berg to the monastery in Mogilno.

As part of Russian reprisals after the failed Polish January Uprising, the Franciscan monastery was closed down in 1864,[4] and in 1867 Radziejów lost its city charter.

[5] In 1933 Radziejów obtained a railway connection as the newly built Polish Coal Trunk-Line passed just 3 km west of the town.

In 1940 hundreds of Poles were expelled, and their houses, shops and workshops were handed over to German colonists as part of the Lebensraum policy.

[6] Local catechist, priest Jan Wieczorek was among Polish teachers murdered by the Germans in the Dachau concentration camp during the Intelligenzaktion.

[5] The ghetto was liquidated in 1942 when its population was transported to Chelmno extermination camp in April 1942[9][10] where they were killed in gas vans by carbon monoxide exhaust.

In 1946 they organized a local branch of the Central Committee of Polish Jews (Centralny Komitet Żydów Polskich), which functioned until 1948 by which time most of its members left Radziejów.

[11] In 1979 a new hospital opened in Radziejów designed to accommodate 272 patient beds (today functioning as Samodzielny Publiczny Zakład Opieki Zdrowotnej w Radziejowie).