In 1788 a notable commercial activist of the final period of the Republic, Tomasz Ostrowski, created a center of the smelting industry in the area that is now Tomaszów Mazowiecki that made use of local iron ore. In 1793 the settlement became a part of the Prussian partition of Poland. From 1805 it was within the Warsaw Principality and, from 1815, within Russian territory (the Congress Kingdom of Poland). In around 1820 the town’s metallurgical plants began expanding. The wool industry gained a hold in the town in 1824 (among others, F. Stumpf's wool mill and the A. Oferman and M. A. Steinman spinning mill), which brought weavers, many of whom were German, to the town. Tomaszów received its town charter in 1830.

The economic decline of the 1830's and 1840's (exacerbated by high Russian import duties) was followed by another period of growth. One of the biggest carpet factories in Europe opened in the town in 1851. In 1885 the town was connected to a railway network, and in 1911 an artificial silk factory was opened.

In the first decade of the 20th century, the town continued to be a significant industrial center. The period 1905 to 1907 saw an outbreak of strikes and workers' demonstrations. Workers clashed with the Russian army and police.

The city had a large concentration of Jews. In 1939, they numbered around 13,000.

On 5th and 6th September 1939, the "Prussia" 13th Infantry Division fought defensive battles in the Tomaszów Mazowiecki region. During the period 1940 to 1942, the German occupiers established a ghetto, through which more than 20,000 people passed, of whom around 15,000 were transported to the Treblinka death camp. Also, between 1939 and 1944, German police arrested more than 2,000 people in the town. Partisans were active in the Tomaszów area, among them the Hubalczycy, the Home Army, and the People's Guard. A division of the People's Guard fought a battle here with the German police and Gestapo on 6th August 1942.

From 1945 to 1949 Tomaszów contained an internment camp for German civilians in Poland. Until 1953 the city was the scene of organized anti-communist activity by, among others, Wolności i Niezawisłości (Freedom and Independence) and the "Underground Army". In 1948 the city became the seat of a District. In 1999, it again became a district seat within the Łódzkie Province.

Based on source materials from the PWN.