| Flagg Township | |
| Settlement Type: | Township |
| Image Map1: | Illinois in United States (US48).svg |
| Map Caption1: | Location of Illinois in the United States |
| Coordinates: | 41.9372°N -89.1106°W |
| Subdivision Type: | Country |
| Subdivision Name: | United States |
| Subdivision Type1: | State |
| Subdivision Name1: | Illinois |
| Subdivision Type2: | County |
| Subdivision Name2: | Ogle |
| Established Title: | Organized |
| Established Date: | November 6, 1849 |
| Leader Title: | Mayor |
| Leader Name: | Susan Plumley |
| Leader Title1: | Supervisor |
| Unit Pref: | Imperial |
| Area Total Sq Mi: | 35.61 |
| Area Land Sq Mi: | 35.52 |
| Area Water Sq Mi: | 0.08 |
| Elevation Ft: | 817 |
| Population As Of: | 2010 |
| Pop Est As Of: | 2016 |
| Pop Est Footnotes: | [1] |
| Population Est: | 13041 |
| Population Density Sq Mi: | 381.8 |
| Timezone1: | CST |
| Utc Offset1: | -6 |
| Timezone1 Dst: | CDT |
| Utc Offset1 Dst: | -5 |
| Postal Code: | 61068 |
| Area Code: | 815 |
| Blank Name: | FIPS code |
| Blank Info: | 17-141-26298 |
| Blank2 Name Sec2: | Wikimedia Commons |
Flagg Township is located in Ogle County, Illinois. As of the 2010 census, its population was 13,562 and it contained 5,525 housing units.[2]
Flagg Township was named for Richard P. Flagg, a pioneer settler.[3]
According to the 2010 census, the township has a total area of, of which (or 99.75%) is land and (or 0.22%) is water.[2]