Edgar (65) will succeed Bill Beatty in February next year and will be the union's president in the most important of years - World Cup year.
ORFU chairman Wayne Graham said the appointment of Edgar was great news and he was thrilled to get someone of Edgar's standing to be the president in such a big year. The role of the president is mainly ceremonial.
The New Zealand Rugby Union wants provincial union presidents next year to be high-profile as they will be busy with World Cup-related activities.
Edgar, who lives in Queenstown, said he felt humbled by the position and, with a new-look board involved in Otago rugby, felt he could contribute.
He played the game at a relatively low level but had been a fan all his life and was involved in commercial ventures such as the All Black Club in the early 1990s.
He is chairman of the Forsyth Barr Group, and earlier this year was voted senior New Zealander of the year.
He was greatly looking forward to the World Cup and the playing of games in the new Dunedin stadium. Forsyth Barr is the naming sponsor of the stadium.
Edgar is the chairman of the New Zealand Winter Games and the former president of the New Zealand Olympic Committee.
Edgar's appointment is another major move for Otago rugby.
Earlier this week, Graham was appointed the new chairman of the board, with former All Black coach Laurie Mains elected deputy chairman.
Otago captain Alando Soakai re-signed last week, while Otago stalwart David Latta agreed to be assistant coach of the Otago team last month.
