It is 34 kilometres south-west of the Sydney central business district, in the local government area of the City of Liverpool.

Casula is the first suburb immediately south of Liverpool on the Hume Highway and the Main Southern railway line between Sydney and Melbourne.

Casula consists of undulating, gently rolling land, with elevations across the suburb being mostly between 30 and 70 metres above sea level.

The Georges River forms the eastern boundary of the suburb, and its western bank is paralleled by a relatively steep escarpment.

The original inhabitants of the Casula area were the Tharawal or "Dharawal" people of the greater Eora nation, an Aboriginal Australian group.

Situated in Leacocks Lane, it originally belonged to politician Charles Throsby, a member of the Legislative Council and an explorer.

This camp became briefly notorious in 1916 when a large mob of soldiers rebelled against the strict training regimen, marched on nearby Liverpool, ransacked and looted several pubs, hijacked several trains to Central station in Sydney and continued their drunken rioting, resulting in the Military Police shooting dead one rioter.

A Liverpool South office was renamed Cross Roads in 1964 and Casula Mall in 1990 and remains open.

Much of the acreage in the central and southern portions were subdivided and developed over the next few decades but even now there are pockets of undeveloped land.

It consists of a Kmart discount department store, a Coles supermarket and approximately forty specialty shops.

In Casula, Christianity was the largest religious group reported overall (51.4%) (this figure excludes not stated responses).