Botha was born in Vryheid, KwaZulu-Natal, and currently plays for Saracens in the Premiership.
“Mouritz is a great acquisition for the Sharks and his experience gained at international level will be hugely beneficial to our squad,” Sharks chief executive John Smit said in a statement.
“He will add significant value and depth to our tight five. We look forward to welcoming him to Durban.”
After helping Saracens win the 2011 Premiership, Botha made his debut for England off the bench, in their 23-19 victory over Wales ahead of the Rugby World Cup in 2011.
He also featured for England in 2012 in both the Six Nations and in all three Tests on England’s tour of South Africa, starting the first two and coming off the bench for the third.
Botha has since accumulated over 110 caps for Saracens and made 10 Test appearances for England.