Romeoville is a village in Will County, Illinois, United States. The village is located 26 mi (42 km) southwest of Chicago on the Gateway Wetlands, directly west of the Des Plaines River. Per the 2020 census, the population was 39,863. It is located in the southwest suburban area of Chicago near Interstate 55 and Interstate 355.

Will County is a county in the northeastern part of the state of Illinois. According to the 2020 census, it had a population of 696,355, an increase of 2.8% from 677,560 in 2010, making it Illinois's fourth-most populous county. The county seat is Joliet. Will County is one of the five collar counties of the Chicago–Naperville–Elgin, IL–IN–WI Metropolitan Statistical Area. The portion of Will County around Joliet uses area codes 815 and 779, while 630 and 331 are for far northern Will County and 708 is for central and eastern Will County.