His former deputy, Fiame Naomi Mata'afa, resigned from cabinet last week, also vacating the Natural Resources and Environment ministerial portfolio.
Speaking on TV3 television, Tuilaepa said he has decided that he would now take on the portfolio, saying the workload is easy without the need for international travel.
But he explained that Samoa can go without both a deputy prime minister and a deputy leader in the ruling party until after the 2021 polls.
