The appointment of Martin had been expected after the United Nations last week set up a mission to help rebuild Libya after the overthrow of Muammar Qaddafi.
Martin, a former Secretary General of Amnesty International, had previously served as the UN special envoy on post-conflict planning for Libya. He is also a former UN special envoy in Nepal.
Earlier this month, Martin told Reuters the proliferation of weapons in Libya was a worry and that the new rulers needed to establish a proper police force and army to replace the many armed groups patrolling the streets.
Martin is expected to lead a mission of up to 200 UN staff with an initial three-month mandate. Their tasks will range from electoral assistance to police training.
The United Nations said it had appointed Finland’s Georg Charpentier, an expert on Africa, as Martin’s deputy.
