In Fribourg, the rule will come into effect on Friday, August 28th. The requirement will apply for everyone in the western Swiss canton aged 12 and above.
In addition to all visitors to shops, bars, restaurants and supermarkets, all staff must also wear masks if they are not protected by a glass pane.
In Valais, the requirement will come into place from Monday, August 31st.
Valais is the eighth of Switzerland's 26 cantons to put in place a mask requirement in shops.
Zurich put in place a mask requirement in shops, restaurants and bars from August 27th.
In addition, Basel City, Geneva, Vaud, Neuchâtel and Jura have all put in place a mask requirement in shops.
Masks have been required on public transport in all Swiss cantons since July 6th.