Judging panel chair Jack Yan said the contestants excelled in different areas but Ms Bohm had "that je ne sais quoi".
"It might be described as her natural effortlessness, where nothing seemed to faze her. Avianca is best equipped to handle the international setting of Miss Universe, and that helped put her into the top place," Mr Yan said on his Lucire website.
Also among the top five were Miss Otago Monique Cooley and Miss Auckland Jennifer Lambly.