The confirmation has come from Powys Teaching Health Board, which said the news serves as a reminder to residents to follow the current Covid guidelines.
No figures have been revealed by the health board but the development comes after confirmed cases in Shropshire and Telford & Wrekin.
Only last week Telford & Wrekin's public health director said the 'Delta' variant was now the dominant strain in the borough amid a rise in cases.
In Powys, health chiefs are responding by calling on people to get tested if they have symptoms, and to make sure they get vaccinated when offered the opportunity.
Stuart Bourne, Director of Public Health for Powys Teaching Health Board. said: "Coronavirus continues to be a major threat to public health, and new variants are circulating. Cases of the Delta variant have now been confirmed in Powys. The Delta variant first appeared in parts of the north of England, including Bedford, Bolton and Blackburn and has spread rapidly since then.
"There is no evidence yet that it is more severe, but it is more transmissible This means that everyone should follow the simple rules of Hands - Face – Space, and everyone who is eligible should complete the full two-dose course of vaccination.
“Throughout June, PCR tests for people with Covid-19 symptoms continue to be available from our testing sites in Brecon, Builth Wells, Machynlleth, Newtown, Welshpool and Ystradgynlais. People can also order these tests by post.
“We have also increased the number of locations where people can drop in to collect Lateral Flow Devices for regular tests if they don’t have symptoms. These are available for anyone who can work from home, for volunteers, and for unpaid carers. Lateral flow devices can be collected from Brecon, Builth Wells, Crickhowell, Hay-on-Wye, Llandrindod Wells, Llanidloes, Machynlleth, Newtown and Ystradgynlais. People can also order lateral flow devices by post.
“And, throughout June we have a rapid walk-in testing centre in Newtown for people who do not have symptoms. This is open to everyone. It is located at the Park Street Day Centre in Newtown and is open seven days a week from 10am to 6pm.”
More information about testing in Powys is available from pthb.nhs.wales/find/ttp