Modulating and templating are two synthetic techniques that have garnered significant attention over the last several years for preparing Hierarchally Porous Metal-Organic Frameworks (HP-MOFs). Herein, by using fatty acids with different lengths and concentrations, which act as dual-functional modulators/templates, we are able to obtain HP-MOFs with tunable mesopores with different diameters and locations. We found that the length and concentration of the fatty acid determine if micelle foration can occur, which in turn dictates the porosity of the resulting HP-MOFs. The HP-MOFs with different mesopores exhibit distinct performances in gas uptake and dye adsorption and the structure-performance relationship is ascribed to the pore diameters and locations. This approach provides a potential universal method to efficiently introduce hierarchal mesopores into existing microporous MOF adsorbents with tunable properties.