The University of Stellenbosch has taken the decision in the wake of a viral video chronicling the challenges and racism faced by black students.
It detailed how some struggled with lessons in Afrikaans, one of the main languages spoken by the white minority.
A student movement that campaigned for change said: "The doors of learning and culture shall be opened to all."
A post on the Open Stellenbosch campaign group's Facebook page added: "The Language Policy Has Fallen", a reference to the nationwide protests last month over tuition fees which used the hashtag #feesmustfall.
It is part of a movement to "decolonise" higher education sparked earlier this year when a student emptied a bucket of excrement over the statue of British imperialist Cecil John Rhodes at the University of Cape Town's campus.
"Language should be used in a way that is oriented towards engagement with knowledge in a diverse society and to ensure equitable access to learning and teaching opportunities for all students," Stellenbosch University management said in a statement, adding that the change would take place from next year.
"Since English is the common language in South Africa, all learning should be facilitated in at least English to ensure no exclusion due to language.
"The University remains committed to the further development of Afrikaans and isiXhosa as academic languages."
An elite South African university is to drop Afrikaans as the language of instruction and teach in English.