Walter has signed a two-year deal and replaces Nathan King, who resigned a year into his two-year contract following a performance review in April.
He is a well-credentialled coach and much will be expected upon his arrival in the city.
Walter enjoyed success during his stint with the Titans from 2013-16, winning three South African domestic titles - one in each format of the game.
He was not available for comment yesterday but in a press release said he was looking forward to being involved in New Zealand cricket which had gone from "strength to strength over the past couple of years''.
"To now be part of the system that feeds the national side is a very exciting challenge and at the same time a wonderful opportunity,'' Walter said.
"I hope I'll be able to make a meaningful contribution to this pipeline and to the future success of the Volts team, and look forward to being an integral part of each player's development.''
Otago Cricket Association chief executive Mike Coggan said he was thrilled the province had been able to attract such a high-calibre coach and revealed New Zealand Cricket [NZC] was helping fund Walter's salary.
"We had some very strong recommendations from key people within NZC about Rob,'' Coggan said.
"He has already been researching our players and knows some of our players just through his work, so he is well ahead of where you would expect him to be at this point of time.
"Also, what we think is exciting is we'll be the first major association to centrally contract a coach. So NZC and Otago Cricket have worked through a partnership approach and he'll be contracted to NZC.
"One of the benefits of that is he immediately becomes ensconced in the NZC environment.''
Coggan said the Otago Cricket Association had been one of the most vocal advocates of a central contracting approach.
The association has had trouble attracting coaches of Walter's calibre in the past and Coggan saw the partnership with NZC as a way of securing "the very best'' people.
"Collectively we were able to offer the right amount of remuneration and the right opportunity for him to grow and to stay here.
"NZC and the major associations have talked about that sort of approach for the last 12 months, so we just took the opportunity to go down that road and it has netted us a world-class coach.''
Walter was contracted to the Titans through to 2017 but has been given a release to join the Volts.
He worked with the Proteas from 2009 to 2013 before joining the Titans, where he was selected ahead of 19 other applicants, including Craig McDermott, Grant Flower and Richard Pybus.
He has also worked for the Delhi Daredevils and Pune Warriors as an assistant coach.
Walter is expected to arrive in Dunedin on September 1 and will start in the role on September 5. Initially his wife, Heather, will remain in South Africa with their baby son, William.
