The ban, which was to start 30 January, has been put back to 30 June.
A senior officer of the Ministry of Natural Resources and Environment confirmed the ban had been postponed to allow local companies to get rid of styrofoam products already in stock, TV1 Samoa reports.
The ban will prohibit the importation and use of all styrofoam products like plates, cups and other containers.
Those who fail to comply with the ban could can face fines of up to $US10,000.
In January last year, Samoa banned single-use plastic bags and straws.