Spontaneous or non‐spontaneous unidirectional fluid transport across multi‐dimension can occur under specific structural designs and ambient elements for porous materials. While existing reviews have extensively summarized unidirectional fluid transport on surfaces, there is an absence of literature summarizing fluid's unidirectional transport across porous materials. This review introduces wetting phenomena observed on natural biological surfaces or porous structures. Subsequently, it offers an overview of diverse principles and potential applications in this field, emphasizing various physical and chemical structural designs (surface energy, capillary size, topographic curvature) and ambient elements (underwater, under oil, pressure and solar energy). Applications encompass moisture‐wicking fabric, sensors, skincare, fog collection, oil‐water separation, electrochemistry, liquid‐based gating, and solar evaporators. Additionally, we have compiled significant principles and formulas from various studies to offer readers valuable references. Simultaneously, we critically assess potential advantages and challenges in these applications and present our perspectives.This article is protected by copyright. All rights reserved