[1][2][3] Bremer is of German ancestry, his father emigrated from Germany to Cape Colony shortly before his birth.

His mother moved with her children to Wellington in the Western Cape where Bremer attended school at the Huguenot College.

Bremer was a reputable doctor at a children's hospital before returning to Cradock with his sick mother.

In 1910 Bremer established himself as a physician at Cradock in the Eastern Cape and was elected to the city council.

During the First World War he served as a medical doctor for the South African troops in East Africa.

From 1939 Bremer was a member of the Medical Council of the Union of South Africa and in 1943 he became the President of the organization.

The Karl Bremer Hospital in Bellville, Western Cape carries his name since its inauguration on June 30, 1956, by Jozua François Naudé.