Kellyville is named after Hugh Kelly, who owned the Kellyville Estate. Kelly owned a hotel on the corner of Wrights and Windsor Roads called the Bus outside Kellyville Post Office on corner of Acres & Windsor Roads Kellyville 1930s
'Bird-In-Hand'. Originally, the area had been known as 'There and Nowhere' followed by 'Irish Town' for the clan of Kellys that lived in the area. After Kelly's death in 1884, John Fitzgerald Burns, James Green and George Withers purchased portions of several early land grants, which were subdivided into farmlets as part of the 'Kellyville Estate', thereby giving the suburb its name. The first subdivisions of 100-acre (0.40 km2) lots were made in 1884.
Kellyville Post Office opened on 1 January 1889.
Parts of Kellyville became separate suburbs. Beaumont Hills, north of Samantha Riley Drive, was renamed in 2002. Kellyville Ridge, west of Old Windsor Road, is a separate suburb in the City of Blacktown.
Kellyville Public School is a historic building which was established in 1849. For most of the 20th century, Kellyville was semi-rural. From the 1960s to the 1980s about 900 homes were developed in an area around Acres Road, known locally as 'The Village'. More recently, major developments such as Kellyville Plaza have encouraged residential growth. Due to the suburb's location, Kellyville is a major growth area in The Hills.