The precaution is being urged to help protect customers and staff from Covid-19 while in enclosed public spaces at council sites, including libraries.
Public safety is the council’s priority, especially for the most vulnerable. Lower infection rates will also help the council maintain its services to the public by keeping staff levels high.
The requirement to continue wearing a mask (unless exempt) is part of a responsibly cautious approach outlined by the Prime Minister in announcing the end of legal restrictions from Monday.
It will also apply to people joining ceremonies led by a registrar from the county council.
Darrell Gale, Director of Public Health for East Sussex, said: “Wearing face-coverings offers some additional protection from catching and passing on the virus. That’s why visitors to the county council’s buildings and people taking part in wedding ceremonies where we officiate are urged to continue to wear a face-covering.
“We want to keep everyone in our communities as safe as possible and we want to ensure that public services aren’t weakened by high levels of infection and illness. Our thanks to everyone in our communities who continues to play their part in protecting each other.”