Johnsburg is a northwest suburban village in McHenry County, Illinois, United States. The population was 6,337 at the 2010 census.
The area that came to be known as Johnsburg was first settled in 1841 when McHenry County was only 5 years old by immigrant families from the Eifel region of Germany, predominantly the Mayen-Koblenz district (Kreis), who were escaping religious persecution and oppressive social conditions. A small group of the newly-arrived Germans –Nicolaus Frett, Nicolaus Adams, Jacob Schmitt and Johann Baptist Muller – settled in this Fox Valley region and formed one of the first Catholic parishes (named St. John the Baptist) in all of Illinois in what was then called "Miller's Settlement." In 1842 they built their first church; the site has continually held a parish church since then. The church, a simple log cabin, dually functioned as a school as well as a meeting hall. The first priest to serve this new congregation was delivered there by friendly Indians who found him lost in the woods of Wisconsin. The church served the community until 1850 when a larger frame church was built to replace it. In 1867 a third church was built in the popular Gothic style of Germany. This beautiful church took thirteen years to complete and was the pride of the Johnsburg community until it was tragically destroyed by a great fire on February 19, 1900. So devastating was the fire that many grave markers of the early settlers, in the adjoining cemetery, were destroyed.