This means that anyone returning from those countries after midnight on Thursday August 6 will need to be quarantined for 14 days.
The decision was taken following a meeting with ministers from the four British countries.
Serbia, Spain and the Spanish islands were all removed from the list of countries exempt from travel restrictions last month.
The changes announced tonight also include the addition of two new countries to the list of non-quarantined countries: Brunei and Malaysia.
In a statement released Thursday evening, Health Minister Vaughan Gething said: “Yesterday I attended a meeting of ministers from the four UK countries to examine the risk to public health posed by an increasing prevalence of COVID-19 in Andorra, Bahamas and Belgium.
“Along with other British ministers, I have also discussed the risk to public health posed by a decrease in the prevalence of COVID-19 in Brunei and Malaysia.
“As a result, the Welsh government will also later today add Brunei and Malaysia to the list of countries and territories exempt from our border sanitary measures.
“Urgent changes will be made to the Health Protection (Coronavirus, International Travel) (Wales) Regulation 2020 which will come into effect from midnight tonight.
“These amendments will mean that anyone arriving in Wales from Andorra, the Bahamas and Belgium or who has stayed in one of these countries or territories in the last 14 days will have to self-isolate for 14 days from tomorrow. .
“Anyone arriving in Wales from Brunei or Malaysia, on the other hand, from tomorrow will not be required to self-isolate for 14 days. ”
While no announcements have yet been made, the rest of the UK is expected to make the same changes.