Hagar Township is a civil township of Berrien County in the U.S. state of Michigan. As of the 2010 census, the township population was 3,671.
The township is in the north of the county with Lake Michigan to the northwest, Covert Township in Van Buren County to the north, Coloma Charter Township to the east, Bainbridge Township to the southeast, and Benton Charter Township to the south.
Charles Lamb and his wife came to the area from Vermont in 1839 to become the first white settlers. The township was officially organized on March 25, 1846.
There are no incorporated municipalities within the township. The unincorporated communities of Riverside and Lake Michigan Beach (also known as "Hagar Shores") are within the township.