Prime Minister Tuilaepa Sailele said the move would help sustain a vital part of the ocean’s ecosystem.
“We will not sit idly by while the demand for shark products robs our future generations of these culturally, ecologically and economically valuable species,” he told the Samoa Observer this week.
“Let us together continue to safeguard these imperilled species for our future generations.”
While Samoa’s landmass is tiny, its waters cover 129,000 square kilometres (50,000 square miles), an area larger than South Korea.
Another Pacific island nation, Palau, created the world’s first shark sanctuary in 2009.
Others such as Kiribati, Cook Islands, New Zealand and Tokelau have followed suit, changing attitudes to the predator and helping curb demand for shark fin soup.