A system and method for producing a liquid hydrocarbon product from a Fischer-Tropsch process using a synthesis gas feed produced in an oxygen transport membrane based reforming reactor. The system and method involve reforming a mixed feed stream comprising natural gas, hydrogen and the Fischer-Tropsch tail gas, in a reforming reactor in the presence of steam, radiant heat from oxygen transport membrane elements and a reforming catalyst to produce a reformed synthesis gas stream comprising hydrogen, carbon monoxide, and unreformed hydrocarbon gas. The reformed synthesis gas stream is further reformed in an oxygen transport membrane based reforming reactor and conditioned to produce a synthesis gas product stream preferably having a H2/CO ratio of from about 1.7 to about 2.2. The synthesis gas product stream is then synthesized using a Fischer Tropsch process to produce the liquid hydrocarbon product and a Fischer-Tropsch tail gas.