The 32-year-old, who was born in South Africa but moved to England in 2004, leaves Premiership Saracens after five and a half seasons.
"Mouritz is a great acquisition for the Sharks and his experience gained at international level will be hugely beneficial to our squad. He will add significant value and depth to our tight five," Sharks CEO John Smit said.
Botha made his England debut in 2011, making 10 appearances in all for his adopted country.
"Saracens will always be important to me, and it's difficult to leave so many friends... but the Sharks are trying to build something special in Durban.
"This will be a great rugby challenge for me and a great adventure for my young family," Botha told his former team's website.
(Reporting by Nick Said; Editing by Ossian Shine)
