Blacktown is an electoral district of the Legislative Assembly in the Australian state of New South Wales.

Blacktown is known as a largely working-class area, and as such, the electorate has tended to strongly support the Labor Party, which has held the seat for all but three years since its inception.

It was briefly marginal during the late 1950s, when long-serving member John Freeman was forced into retirement after trying and failing to find a safer seat.

Liberal Alfred Dennis won the seat in the 1959 election, but held it for only one term before Labor regained it.

It is the only time since the 1950s that Labor has not won an outright majority of the primary vote in the seat.