Mains, who coached Otago from 1983 to 1991, and then the All Blacks from 1992 to 1995, has not been involved in Otago rugby since he finished coaching the Highlanders in 2003.
That year he had a falling out with some players and with Highlanders chief executive John Hornbrook.
Otago District Heath Board chief medical officer of health Richard Bunton also confirmed yesterday he would stand for the board while board member Tony Chave said yesterday he would not seek re-appointment.
Mains (63) said he was standing for two main reasons.
"I feel I can make a significant contribution to help improve Otago rugby and can be there to support those talented individuals who in recent years have been elected to the board.
I can get on the board and support them to make the changes which need to be made," he said.
He said grassroots rugby from schools, clubs and the sub-unions had been neglected in past years and felt that had to be better managed.
"I'm also a strong supporter of the new stadium and if the stadium is to succeed and not be a burden on the ratepayers of the DCC then Otago rugby has to be performing."
Mains said he was approached by a few individuals before Christmas and had spent a lot of time over deciding whether to stand.
"I think I have something significant to offer and if I didn't then I wouldn't have stood.
"Otago rugby is clearly still very important to me and has been a significant part of my life."
He believed Otago had a strong group of players, which only had to be enhanced by the import of a couple of players and a better talent identification programme.
The union posted a $764,000 loss for last year and Mains believed his business background would help on the board.
Until he got on the board, he could not say in detail what needed to be done.
Mains lives in Queenstown but had sold his building business in the resort town, although he still runs a house building business in Dunedin.
Bunton, who played 14 games for Otago in the 1970s, said he was approached about standing and it had always been in the back of his mind to make a contribution.
"I'm of a realistic enough view that one person can not make big changes but if I can join with people who think along similar lines then we can secure the future of the game and the future of the new stadium," Bunton said.
He said when rugby was going well in Otago there had been no planning for the future, and that was coming back to haunt the union.
Bunton (56) said he was aware Mains was standing, and said he did not have a set tunnel vision on what had to be done to make the union successful.
Chave said he would not be seeking re-appointment after being on the board since 2002, citing increasing work commitments.
Another spot is open on the board after Ross Laidlaw resigned in November last year to be the chairman of the Highlanders board.
Chairman Ron Palenski is the other board member up for re-appointment and he has yet to decide whether he will stand again.
