Single-layered FePt thin films were deposited on glass substrates and subsequently annealed at 800 °C for various times in a rapid thermal annealing (RTA) furnace. Near-fully-L10-ordered FePt films were obtained after RTA. The accumulation of the intrinsic tensile stress is mainly contributed by the densification reaction, which leads to the development of (001) preferred orientation. The relief of the tensile stress predominantly stems from the microstructural variation (from continuous to interconnected network state), resulting in a reduction of (001) texture. Enhanced perpendicular magnetic and crystalline anisotropy was obtained for the films annealed for 900 s, confirmed by a high Lotgering orientation factor of 0.99 and differential squareness of 0.5. The results provide direct evidence that intrinsic tensile stress prompts the (001) preferred orientation through suggested strain-induced grain growth.