Lees' surprise appointment has come about through a reshuffle in the Otago coaching ranks.
Otago assistant coach Mohit Rao has resigned after agreeing to stay on with the Hong Kong Cricket Club for the next two years to help develop and promote the game there.
Former Sparks coach Nathan King will replace Rao in the Volts coaching staff, leaving a vacancy that Lees was happy to fill.
Lees is well known in the province, having forged a long and successful playing career before going on to hold significant coaching and administration positions in the sport.
Lees moved back to Central Otago in April last year and has been enjoying "semi-retirement" in Clyde.
Recently, his involvement in the sport has been limited to coaching at grassroots level and meeting his broadcasting commitments.
But when Otago cricket called, Lees could not say no.
"I spoke to Ross [Dykes, Otago Cricket chief executive] and he said there was a bit of a need," Lees said.
"So I said I will fit in if that is what he wanted. I'm just filling a bit of a gap for them, but I like the idea.
"I've always harboured a soft spot for the province and like the idea of a wee bit of a challenge. And because the time commitment is not huge, it fits in absolutely perfectly."
Dykes said the association was lucky to have someone of Lees' calibre to call on.
"How fortunate we are in Otago cricket that we can lose the services of a skilled practitioner in Mohit Rao and effectively replace him with the highly experienced and respected Warren Lees," he said.
"We take great pride in promoting our own and it is a real thrill to see Nathan King take a new step in his coaching career and, at the same time, welcome back such an icon of our game as Warren Lees."
Lees, a wicketkeeper-batsman, played 108 first-class games for Otago, 81 as captain.
He scored 3754 runs at 25.36, took 220 catches and effected 36 stumpings in a playing tenure in which Otago won two one-day titles and four first-class titles.
