Ms Townsend, who has 20 years of experience, will replace former chief executive Richard Smith who retired in January 2015.
Funds SA chair Dr Helen Nugent said the appointment, which is effective from 20 April 2015, was made by the South Australian Governor Hieu Van Le after an "extensive and rigorous selection process".
"The board of Funds SA is delighted that Jo Townsend has accepted the role of CEO and looks forward to working with her to the benefit of all stakeholders," said a statement.
Funds SA is the specialist investment manager for South Australia public superannuation schemes and the long-term investment funds of nominated state government agencies.