Borg was a teacher. After having seen a play where a deaf boy communicated by gestures, he was inspired to create a manual alphabet. He began to educate deaf and blind students regularly in 1808. He founded Allmänna institutet för Blinda och Döfstumma (The Public Institute of the Blind and Deaf) in Stockholm in 1809 with protection from the Queen, Hedwig Elizabeth Charlotte. His perhaps most famous student was Charlotta Seuerling. The school had deaf teachers, and the education was given by sign language. He made a trip to Portugal in 1823–28, where he founded a school for the deaf; thereby, Portugal was given the same manual alphabet as Sweden.
He was the guardian and mentor of Johanna Berglind, also she an important figure in the history of the education of the deaf in Sweden.
^a Sign-language names reflect the region of origin. Natural sign languages are not related to the spoken language used in the same region. For example, French Sign Language originated in France, but is not related to French.