The 38-year-old left-arm pace bowler began his international career with the Dutch but switched allegiances and went on to play for Australia, where he was the leading wicket-taker at the 2010 World Twenty20 in the Caribbean.
He took 14 wickets at an average of 13.07.
He will join Ryan ten Doeschate, who is also of Dutch extraction, as the Volts' second overseas professional.
Ten Doeschate is in his third season with the Volts and will captain the twenty20 side.
The pair will arrive in New Zealand later this month in time for Otago's opening game against Auckland in Hamilton on November 1.
Nannes, who went very close to representing Australia in skiing at the Winter Olympics, is these days a twenty20 specialist who has lent his services to a long list of different teams, including IPL teams the Chennai Super Kings, Delhi Daredevils and Royal Challengers Bangalore.
He has played 203 twenty20 matches and boasts a record of 246 wickets at an average of 21.59 and economy rate of 7.28.
He picks up a wicket every 17.7 deliveries and will bring plenty of pace and aggression to the Volts.
But most importantly, he brings a wealth of experience, Otago coach Dimitri Mascarenhas said.
''He is a massively experienced cricketer, he's a wicket-taker and he has a proven record,'' Mascarenhas said.
''He has played over 200 games, taken nearly 250 wickets in this format and will just be an absolute asset for us. It is not only what he brings [on the field] but what he will offer our young bowling attack. For them to be able to learn from him is stuff that you cannot buy.
''Dirk will be around for six weeks and Jake [Jacob Duffy] will be about to pick his brain for that whole time.''
Mascarenhas said it had not cost a fortune to secure his signature, either.
''I knew we needed bowling options so I just rang him and said, 'Mate, would you be keen? We don't have a hell of a lot of money to offer you'. He was just more than happy to help. It is a great lead up for the Big Bash for him, so it worked out brilliantly.''
Otago will play Canterbury in a two-day warm-up match in Rangiora beginning tomorrow and one-day games against Scotland and Ireland in Lincoln next week.
Jesse Ryder has been left out of the two-day side but will also play in the one-dayers, while Otago Boys' High School pupil Josh Finnie has also been named in the one-day squad.
''Jesse has played a hell of a lot of cricket recently and we just think he is very keen to work on his fitness and he has been doing that brilliantly."
But he will be ready for the one-day games at Lincoln.
Finnie's inclusion ''is just an opportunity for him to come in ... and show what he has got''.
''If he gets an opportunity, it will be great to see him.''
Left-armer Craig Smith had an impressive trial but has missed selection though he is still on the selectors' radar, Mascarenhas said.
''His circumstances are a little bit different because he lives [and works] down in Invercargill. We know he is there and we know what he can do. He is one we are definitely looking at.
''You need a good stock of fast bowlers nowadays, so he will be there or thereabouts.''
Otago cricket
The teams
To play Canterbury: Roald Badenhorst, Nick Beard, Michael Bracewell, Mark Craig, Derek de Boorder, Ryan Duffy, Tipene Friday, Aaron Redmond (captain), Brad Rodden, Hamish Rutherford, Bradley Scott, Neil Wagner, Sam Wells.
To play Scotland and Ireland: Badenhorst, Beard, Bracewell, de Boorder, Jacob Duffy, Ryan Duffy, Josh Finnie, Friday, James McMillan, Redmond (captain), Iain Robertson, Rutherford, Jesse Ryder, Scott, Wells.
