The village includes land in Plainfield and Wheatland townships. Part of Plainfield is located in Kendall County ( Na-Au-Say and Oswego townships). With the growth in the Chicago suburbs in the 1990s and 2000s, the village has seen a population increase, from 4,500 in 1990 to 28,000 in 2000 to over 37,000 in 2007.
The village has established a community Preservation Commission and historic preservation ordinance. It is the home of the Lake Renwick Preserve, a county forest preserve used for birdwatching and other activities.
The area was called Walkers' Grove until it was platted as Plainfield in 1841. It was originally settled by a large community of Potawatomi, and the land was later bequeathed to the United States as part of the Treaty of St. Louis (1816) with the Council of the Three Fires. Indian Boundary Road aligns with the western border of the tract of land originally ceded.
The earliest Europeans in the area were French fur traders. The first European settler in the area was James Walker, who traveled with his father-in-law, Methodist Reverend Jessie Walker traveled here in 1826 where he established a small mission for the Potawatomi Indians. James Walker, Jesse Walker's son-in-law, traveled with him and became the first European to claim land in the area in 1828.
In 1828, James Walker, in the company of several men, erected a sawmill around which the settlement of Walkers' Grove developed.
Plainfield is identified as the oldest community in Will County because the earliest settlement of Walkers' Grove was established on the banks of the DuPage River by 1828. However, the actual Village of Plainfield was platted immediately north of Walkers' Grove in 1834 by Chester Ingersoll. The separate community of East Plainfield was platted in June 1836 by James Mathers who began selling lots in July 1836. In addition he also constructed a gristmill and a mill race west of Water Street. Water Street would later become Plainfield-Naperville Road. Ingersoll's Planefield (Plainfield)which comprised lots in Section 16, along with Mather's East Plainfield lots in Section 10 and Levi Arnold's plat of Section 9 all became joined to create the present-day village after the death of Levi Arnolds in 1845.
Walkers' Grove flourished because of the DuPage River and established routes to Fort Dearborn in Chicago, as well as to Ottawa. Reuben Flagg hauled lumber from Walker's mill to Chicago in order to erect the first two frame structures in the city (P.F.W. Peck House and the George Dole Forwarding House). Chicago also depended upon the settlement for mail and supplies.
The community's early prosperity was stunted when the Illinois & Michigan Canal opened in 1848, because the Village was not located along the canal. Located within the Village are numerous Greek Revival, upright-and-wing cottages, a school built in 1847, and a number of early-19th-century homes. Plainfield currently has three buildings listed on the National Register of Historic Places: Plainfield House, Flanders House and a 1928 Standard Oil Gas Station. 
North Central College was first founded in the village in 1861 as Plainfield College.
Plainfield Public Library District was first founded in the village in 1925 as the Nimmons Village of Plainfield Free Public Library.
Plainfield is also the birthplace of Eddie Gardner, one of the pilots credited with establishing the transcontinental air mail routes for the United States Postal Service. The earliest architects associated with buildings in Plainfield are J.E. Minott of Aurora; G. Julian & John Barnes of Joliet; and Herbert Cowell of Joliet and Plainfield.
On August 28, 1990, the Plainfield Tornado, an F5 tornado, went through the Village and parts of Crest Hill and Joliet, killing 29 people and injuring hundreds. A population explosion started to take form at the end of the 20th century after the tornado. This made way for a large number of new home subdivisions. Before the population boom, Plainfield was primarily an agricultural town.
Certain older parts of Plainfield have suffered from extreme traffic congestion. Before Interstate 55 was built just east of the town in the late 1950s, U.S. Route 30, The Lincoln Highway and U.S. Route 66 (sometimes referred to as "The Mother Road") merged into one street for three blocks on what is now Illinois Route 59. This merge is now only shared by U.S. 30 and Lincoln Highway, between Plainfield/Joliet Road on the south to Lockport Street on the north, but continues to be an area of heavy traffic congestion even outside heavy commuting periods. At one time, the two longest paved highways in the world ( Lincoln Highway and U.S. Route 66) crossed within Plainfield. The highways only crossed each other twice and both locations are in Will County. The other location is in neighboring Joliet.
Plainfield is located at (41.617280, -88.202837).
According to the 2010 census, Plainfield has a total area of 24.199 square miles (62.68 km 2 ), of which 23.22 square miles (60.14 km 2 ) (or 95.95%) is land and 0.979 square miles (2.54 km 2 ) (or 4.05%) is water. 
Like its namesake, Plainfield's topography is generally flat. Thousands of years ago, land in greater Plainfield used to be part of the bed of proglacial Lake Wauponsee. However, the lake did not hold up long, and eventually drained into the Illinois River valley.  The lake left behind a very flat landscape. Much of downtown Plainfield has an above sea level elevation of around 600–625 feet (183–191 m), with some areas in the western and northwestern portions of the village's outskirts exceeding 700 feet (210 m). This rise in elevation was created by terminal moraines that were formed during the Wisconsin Episode of the last ice age's last glacial period that has been recorded.
As of the census of 2000, there were 13,038 people, 4,315 households, and 3,521 families residing in the village. According to a 2003 special census, the village has a population of 20,673. The population density was 1,122.8 people per square mile (420/km²). There were 4,609 housing units at an average density of 396.9 per square mile (153.3/km²). The racial makeup of the village was 95.85% White, 0.84% African American, 0.08% Native American, 1.25% Asian, 0.01% Pacific Islander, 1.01% from other races, and 0.96% from two or more races. Hispanic or Latino of any race were 3.87% of the population.
There were 4,315 households out of which 47.3% had children under the age of 18 living with them, 73.6% were married couples living together, 5.7% had a female householder with no husband present, and 18.4% were non-families. 14.8% of all households were made up of individuals and 4.2% had someone living alone who was 65 years of age or older. The average household size was 3.01 and the average family size was 3.37.
In the village the population was spread out with 31.9% under the age of 18, 6.3% from 18 to 24, 36.2% from 25 to 44, 19.4% from 45 to 64, and 6.3% who were 65 years of age or older. The median age was 33 years. For every 100 females there were 100.6 males. For every 100 females age 18 and over, there were 96.7 males.
According to a 2014 estimate by the U.S. Census, the median income for a household in the village was $111,536.  About 1.0% of families and 1.8% of the population were below the poverty line, including 2.2% of those under age 18 and 2.3% of those age 65 or over.
A 2014 census estimate pegged the city's population at 42,138.
Major highways in Plainfield include:
The Suburban Chicago PACE bus system expanded two routes (755 and 855) to Plainfield beginning May 6, 2013. Both routes are " bi-directional, weekday rush hour service"  from the Plainfield Village Center to Downtown Chicago. One route terminates in the Illinois Medical District and the other in Chicago's East Loop. 
Plainfield Community Consolidated School District 202 serves Plainfield and portions of Joliet, Crest Hill, Bolingbrook, Romeoville, and Plainfield Township in unincorporated parts of Will County,.
As of the 2012-2013 academic year, the school district spanned a 64-square mile area and served 28,728 students. 
|High School||Established||School District||Location||County|
|Plainfield Central High School||1959||Plainfield Community Consolidated School District 202||24120 Fort Beggs Dr, Plainfield, IL 60544||Will|
|Plainfield South High School||2001||Plainfield Community Consolidated School District 202||7800 Caton Farm Rd, Plainfield, IL 60586||Kendall|
|Plainfield North High School||2005||Plainfield Community Consolidated School District 202|| 12005 S 248th Ave, |
Plainfield, IL 60585
|Plainfield East High School||2008||Plainfield Community Consolidated School District 202||12001 S Naperville Rd, Plainfield, IL 60585||Will|
- Kapri Bibbs, American football runningback with the Denver Broncos ; Bibbs was raised in Plainfield and played for Plainfield North High School's varsity football team. Bibbs won Super Bowl 50 with the Denver Broncos.
- Lisa Chesson, Olympic defenseman with the U.S. women's ice hockey team ; was born in Plainfield and played on Plainfield Central High School's varsity hockey team
- Nate Fox, power forward and center with several European teams
- John Henebry, US Air Force General; born in Plainfield
- Melissa McCarthy, actress; born in Plainfield
- Alexander Ratiu, Romanian political prisoner; priest at St. Mary Immaculate Church (1975–1982)
- Warren L. Wood, Illinois politician; lived in Plainfield