Kenyans producing, selling or even using plastic bags will risk imprisonment of up to four years or fines of $40,000 from last Monday, as the world's toughest law aimed at reducing plastic pollution came into effect.
The East African nation joins more than 40 other countries that have banned, partly banned or taxed single use plastic bags, including China, France, Rwanda, and Italy.
Kenya's law allows police to go after anyone even carrying a plastic bag.
But Judy Wakhungu, Kenya's environment minister, said enforcement would initially be directed at manufacturers and suppliers. "Ordinary wananchi will not be harmed," she said.
Big supermarket chains like France's Carrefour and homegrown retailer Nakumatt have already started offering customers cloth bags as alternatives.
The environment agency said it would send out its inspectors and environment police to inspect whether manufacturers and citizens had complied with the ban.