Casual employees and unfair dismissal eligibility
Casual status does not automatically exclude you, but working on a regular and systematic basis is part of what the Fair Work Commission checks.
Casual employees are not automatically excluded from unfair dismissal protection, but the Fair Work Commission's guidance adds a condition specific to casuals into its eligibility list: alongside the minimum employment period and the high income threshold, a casual employee also needs to have been working on a regular and systematic basis.
Where casual status shows up elsewhere
Casual employment status also affects two other counts on this site: the small business headcount excludes casuals unless they are engaged on a regular and systematic basis, and the deductions the Commission makes when calculating compensation can include wages or income earned since the dismissal. This guide covers eligibility specifically; the small business definition and the compensation formula are each covered on their own guide.
What this site has not sourced
The precise legal test for what counts as "regular and systematic" casual work, beyond the phrase itself as the Fair Work Commission's guidance uses it, was not opened in detail this session. If your eligibility turns on this specific question, it is worth reading the Fair Work Commission's own guidance directly rather than relying on this general summary.