It ruled that the charges against Theo Bronkhorst "were too vague to enable to him to mount a proper defence".
His lawyer, Perpetua Dube, told the BBC the offence did not have the force of the law and was not criminal in nature.
American dentist Walter Palmer who killed the famed lion last year was not charged.
The lion - a favourite at Hwange National Park - was shot by Mr Palmer with a bow and arrow.
He is said to have paid about $50,000 (Â£32,000) to hunt the lion.
Cecil's killing sparked international outrage, and prompted a global campaign to end lion trophy hunting.
Mr Bronkhorst said in court that he had obtained all the permits required to kill an elderly lion that was outside the national park boundaries.
He is now a free man, though the state could still press fresh charges, the BBC's Shingai Nyoka in Zimbabwe's capital Harare reports.
Cecil attracted photographic safaris and was part of an Oxford research project into lions at the Hwange National Park.
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A Zimbabwe court has dropped charges against a professional hunter alleged to have helped an American dentist to kill a famous lion named Cecil.