Kleinburg is an unincorporated village located in the city of Vaughan, Ontario, Canada. It is home to the McMichael Canadian Art Collection, a major art gallery, and the Kortright Centre for Conservation. In 2001, the village and its surrounding communities had a population of 4,595; the village itself has 282 dwellings, with a population of 952. Kleinburg comprises a narrow section of hilly landscape situated between two branches of the Humber river. The historic village is bounded by Highway 27 on the west and Stegman’s Mill Road to the east The village is located between two branches of the Humber River, and features dense forests throughout its 1.05 km² of land area. Its northern and western peripheries are primarily agricultural. Kleinburg was founded by John Nicholas Kline Sr (1825–1854), a German-Canadian settler. A direct German translation of Kleinburg is "small town". Residents argue that the Town of Kleinburg could be named after its founder or after its landscape (though the latter would necessitate the spelling "Kleinberg", "Small Mountain" in English).

In its early days, Kleinburg was dependent on its many flour and wheat mills, located off the Humber River. The large housing developments began in the 1950s in the west and continued in the 1970s southeast of Kleinburg, in 1993 in the south, 1998 sporadically in the northeast, 1990s south of Kleinburg and the 2000s to the north.

Kleinburg has historically been a small, quiet town, but now attracts many affluent visitors and residents. During its major expansion in the 1990s and early 2000s, many new large homes were built. The homes north and west of Nashville Road typically cost more than one million dollars. Older, larger and more established properties are valued more than this, while homes built near conservation areas and the Humber River are by far the most expensive.

Kleinburg has a historic commercial district containing many heritage buildings and new developments with mixed residential and commercial uses. Main street has local shops and restaurants as well as national chains such as Starbucks and Royal Bank.

Local attractions include McMichael Art Gallery, Kortright Centre, Humber River Trails & Bindertwine Park, Copper Creek Golf Course, and The Doctor's House. The Pierre Berton Discovery Centre is in the final stage of planning and is expected to open in 2014.

Kleinburg is less dependent on immigration than most communities in the Greater Toronto Area; as of 2001, only 20 per cent of residents settled from other countries, the majority of those from Italy, Germany, the United Kingdom, South Africa and Guyana. Most of these (86 per cent) settled in Kleinburg before 1971.

Kleinburg is not an incorporated entity; it has no political jurisdiction and no geopolitically-defined boundaries. Residents vote for a councillor in ward 1 of Vaughan City Council.

The community of Nashville, though distinct from Kleinburg, is considered a suburb of Kleinburg. Residents of Nashville receive many of their services, such as postal and medical services, within Kleinburg.

Most non-Catholic students were once bused to nearby King City Secondary School in King City. But since the opening of Emily Carr Secondary School, busing was eliminated, forcing students to walk far to get to the school as not even public busing services the area. There are not enough students for Kleinburg's own secondary school. However, there is a private school in the area, known as The Hill Academy (K-12). In 2008, the oldest and most historical school, Kleinburg Public Elementary school, was demolished and a new public elementary school by the same name was built and opened in September 2009.

There are 5 schools in Kleinburg: • Kleinburg Christian Academy (Private Elementary) • Kleinburg Public Elementary School (Public Elementary) • Ecole La Fontaine (French Public Elementary School) • Montessori School of Kleinburg (Private School) • The Hill Academy (Private Secondary for student-athletes)