The Kratom plant has been removed from a list of narcotics listed under the amended Narcotics Act.
Justice Minister Somsak Thepsutin said the Act has been modified and the new version was published in the Royal Gazette on Wednesday to annul the plant's narcotics status.
The amendment will take effect on Aug 24, Mr Somsak said.
He thanked the organisations involved in pushing for the plant's removal from the list, noting Kratom is a part of local people's lifestyle.
However, cultivation of the plant will still be restricted until a new law to regulate kratom plantations is enacted, the justice minister said.
He said this legislation, also known as the Kratom Law, will detail how the plant is allowed to be used.
It has currently been approved by the Council of State, and the Justice Ministry will forward a proposal to the cabinet.
The ministry has worked with the Food and Drug Administration on an announcement declaring the legality of kratom.
Regarding ongoing criminal cases, the Office of the Narcotics Control Board (ONCB) has been ordered to identify cases that have not been finalised.
It is expected to drop pending cases after the law comes into effect.
Kratom is typically used in traditional medicine.
However, the plant is known to have stimulating effects on the mind, which makes it a popular recreational drug -- one of the reasons why it was classified as a narcotic for many years.