The appointment comes nearly two weeks after former leader Jane Sterk announced her resignation on Twitter.
At the time, Sterk had said she was ready for new adventures, and that she hoped Andrew Weaver, the first-ever Green party member elected to the B.C. legislature, would consider taking her place.
While Weaver said he was not interested in becoming the party's interim leader, he also also said he may one day run for head of the party.
Olsen, a member of the Tsartlip First Nation, is 37 years old and a partner in a family business that consults on improvements to First Nations housing issues.
He was nearly 400 votes behind the NDP's Gary Holman, who won the Saanich North and the Islands riding in May's provincial election.
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