<p>Internal concentration polarization (ICP) in the support layer significantly decreases the water flux performance of forward osmosis (FO) membranes. To overcome this, we developed a novel method for creating a highly porous support layer using ZIF-67 nanoparticles as a sacrificial template. The ZIF-67 nanoparticles were synthesized in a polymer casting solution at different precursor concentrations, including Co²⁺ and 2-methylimidazole. This method enhances nanoparticle dispersion in the support layer and enables scalable membrane fabrication. ZIF-67 nanoparticles are incorporated into the support layer matrix during phase inversion, then removed by immersing the ZIF-67-incorporated support layer in water, yielding a porous support layer. The modified support layer exhibited a porosity of 83%, which is 15% higher than that of the unmodified membrane, attributed to the templating effect of ZIF-67 nanoparticles. The performance of TFC-FO membranes was evaluated in a FO setup to correlate improved support layer characteristics with FO separation performance. The TFC-2 membrane (fabricated with 3.0 wt.% ZIF-67 precursors) exhibited water fluxes of 29.5 LMH (in FO mode) and 56.4 LMH (in PRO mode), representing a 2.3-fold increase compared to that of the control TFC membrane (13.2/24.6 LMH in FO/PRO modes, respectively). Additionally, the structural parameter decreased from 593&#xa0;µm in TFC to 242&#xa0;µm in TFC-2 membranes, indicating a substantial reduction in ICP. These results demonstrate that the in-situ synthesis of ZIF-67 as a sacrificial template is a simple and effective strategy for preparing high-porosity support layers with reduced ICP.</p>