The decision was announced on the Facebook page of the provincial health office.
The unlocking measure means people can travel to and from Koh Yao and Koh Yao Yai, provided travel is kept within the province.
Shops, however, will still have to close at 10pm in line with the nationwide night-time curfew.
Koh Yao and Koh Yao Yai have been under lockdown since April 9 in a bid to curb the contagion.