Toongabbie is noted for being the third mainland settlement (after Sydney and Parramatta) set up after the British occupation of Australia began in 1788, although the site of the settlement is actually in the separate suburb of Old Toongabbie.
Governor Phillip established a government farm and convict station on 640 acres (259 ha) in 1791 to grow food for the colony. It was supplement to the farms already established at Rose Hill. By December 1791 there were 500 men working at clearing the land. After eleven years, the government farm was closed and the land was given as grants to settlers and convicts who had done their time.
In 1860, the railway was extended to Blacktown but it took 20 years before any arrangements were made for trains to stop at Toongabbie. The first school in Toongabbie - Toongabbie Public School, opened on the 3rd of May 1886. By April 1911, the school closed due to low enrolments. The school reopened February the next year and has stayed open ever since.
The first post office in the area was opened after many years of campaigning by local residents in 1887 in a private house on Old Windsor Road and this arrangement continued until the 1960s. The first post master was a Mr Birks and he was paid 25 pounds a year to manage the office and bring the mail bag over from Seven Hills on horseback each day. By 1922 the number of residents and businesses had grown sufficiently to support a second office in a weatherboard cottage in Wentworth Avenue, known as Toongabbie West. A purpose built office was opened in the main shopping area in Portico Parade in 1960 becoming Toongabbie Post Office whilst the old Toongabbie Post Office was renamed Old Toongabbie.
The Emu and Prospect Gravel and Road Metal Company Limited opened a private railway line from Toongabbie to Prospect Quarry on 7 April, 1902. Following the inability of the Government railway to supply rail wagons, trains stopped running on the line in 1945, however the rails remained in situ until the early 1960s.
In 1908, what was probably the second scout group formed in Australia, 1st Toongabbie Scout Group was organised by Errol Knox (later knighted for his services to journalism). The first scout hall was a barn on his parents' property, "Montargis" in Binalong Road. Later, in 1934, the Group moved to its present location in Bungaree Road on donated land which had also once been part of the Knox landholdings. The first bank branch in Toongabbie, The Commonwealth Bank, opened in 1957 although bank agencies had operated in the area.
Toongabbie was connected to electricity in the mid-1920s and to town gas and mains sewerage in the mid-1960s. The biggest increase in population occurred after World War II. A sizable area west of the shopping centre, which had previously been farmland and orchards, was subdivided into a housing development called "The Old Roman Estate"; several streets in the area have Roman names, including Marcia St, Lavinia St, Portia St, Lucretia Rd and Portico Parade.
A small shopping centre and supermarket, the Piccadilly Centre, was built in the 1960s in the area bounded by the Toongabbie Hotel and the Catholic Church. This operated until 2004 when the shopping centre and surrounding properties were purchased by a developer for Portico Plaza.
The shopping precinct for many years included a small suburban cinema, the "Rocket", located opposite the railway line, next to the overhead road bridge. It operated from sometime between the wars until the early 1970s, when it was closed and demolished and replaced by a row of shops.
Toongabbie railway station is on the Western line of the CityRail network. The original unstaffed station opened on the 26th April, 1880 and was upgraded over the years with additional platforms and loading facilities. In the late 1880s the first rail official was appointed to manage the station, a Miss Amy Arnold. The current station was opened in 1946 and the line was electrified in 1955.
To the west, the next station on the line is Seven Hills and to the east Pendle Hill.
Toongabbie is also served by private buses with connections to Blacktown via Blacktown Road, Seven Hills via the Prospect Highway, Sydney, and both Parramatta and Westmead via the Great Western Highway.