Founded in 1922, it has nine factories and three technology centers in the United States, Mexico, Europe and Asia, and has sales offices in 16 countries.

The first swaged cartridge heater, the patented device greatly increased heat transfer efficiency.

Shortly after this time, Watlow grew exponentially both globally and domestically, adding facilities in Kronau, Germany, and Columbia, Missouri; and acquiring the Claud S. Gordon Company of Richmond, Illinois, the nation’s leading manufacturer of temperature measurement devices.

The EEOC alleged that the firings amounted to unlawful discrimination based on national origin, and that Watlow Batavia Inc.'s workplace lacked the safety-related conditions that make an English-only policy permissible.

[12] In 2022, Watlow acquired Eurotherm from Schneider Electric, expanding the company’s presence in Europe and product offering in sophisticated thermal controls.