The "Chief Nazim" a.k.a District Nazim is elected by the Nazims of Union Councils, Union Councillors and by Tehsil Nazims, who themselves are elected directly by the votes of the local public.
Pakistan originally had a system, inherited from the time of British rule, in which a Mayor was the head of a district. However under the Local Government Act, the role of the Nazim is different from that of a Mayor with more power. The Nazim System was introduced after the Commissionerate system, that was imposed during British rule, was lifted by the Government of Pakistan. Now there is no Commissioner for any of the division, Deputy Commissioner for the districts and Assistant Commissioners, after the Local Government act was imposed in the country in 2001, except Islamabad, the federal capital where still the Commissionerate system is running.