Hydroxyl functionalized polytriazole-co-polyoxadiazole (PTA-POD) copolymers have been synthesized and cast as highly thermal stable, chemical resistant and anti-organic/biological fouling porous substrates for the fabrication of thin-film composite (TFC) forward osmosis (FO) membranes. The roles of PTA/POD ratios in the membrane substrates, TFC layers and FO membrane performance have been investigated. This study demonstrates that the substrate fabricated from the copolymer containing 40 mol % PTA is optimal for the TFC membranes. Compared to the POD-TFC membrane, the 40 mol % PTA-TFC membrane exhibits a remarkable decrease in structural parameter (S) of more than 3.3 times. In addition, the 40 mol % PTA-TFC membrane is characterized by high water fluxes of 24.9 LMH and 47.2 LMH using 1 M NaCl as the draw solution and DI water as the feed under FO and pressure retarded osmosis (PRO) modes, respectively. Compared to a polysulfone (PSU) supported TFC-FO membrane under the similar fabricated conditions, the 40 % mol PTA-TFC membrane shows better FO performance and enhanced anti-fouling properties on the support (lower protein binding propensity and improved bacterial inhibition). Moreover, the performance of the 40 mol % PTA supported TFC-FO membrane could be improved to 37.5 LMH (FO mode)/78.4 LMH (PRO mode) with first steps of optimization. Hence, the use of newly developed hydroxyl functionalized polytriazole-co-polyoxadiazole copolymers may open up a new class of material for FO processes.