Always Vegas, Gibson Casino, Malibu Club Casino and Viggoslots will be blocked after ACMA investigations found that the sites were operating in breach of the 2001 Interactive Gambling Act.
The ACMA, which said it received a number of complaints about the websites, has urged customers who have an account with the sites to withdraw any funds as soon as possible.
Since the ACMA made its first blocking request in November 2019, some 180 illegal gambling websites have been blocked.
More than 100 illegal operators have also pulled out of the Australian market since the ACMA started enforcing new rules for offshore gambling in 2017.
The latest order means that the ACMA has requested more than 30 websites be blocked so far this year.