His lawyers welcomed the decision.
Lamichhane, 23, has been the face of cricket in Nepal and the only player from the Himalayan country to take part in prominent Twenty20 leagues in India, Australia, Pakistan and West Indies.
The leg-spinner, who played for the Hobart Hurricanes in the BBL, was suspended as Nepal's captain and taken into custody after police issued an arrest warrant for him over the assault in 2022. He was later released on bail.
Kathmandu district court sentenced him to eight years in jail in January and said he should also pay about $US3,770 ($A5,600) as a fine and compensation to the victim.
Lamichhane's lawyers said the High Court concluded the hearing on his appeal and set him free.
"He had to be cleared and the high court has set him free. He was not guilty," Sabita Bhadari Baral, a lawyer for the player told Reuters after the court verdict, details of which are yet to be released.
A jubilant Lamichhane appeared at the court premises after the verdict. His supporters blew traditional musical pipes and beat drums to celebrate.
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