This study reports the generation of a strong spin-transfer torque (STT) in a topological insulator (TI) thin film, Bi₂Se₃, when an in-plane current flows through it. The torque is directed in a manner consistent with the helical spin-momentum locking of the TI surface state. The results show that the strength of the torque per unit charge current density in Bi₂Se₃ is greater than that of any previously measured spin-torque source, even in non-ideal TI films where surface states coexist with bulk conduction. The mechanism involves the spin accumulation generated by the TI surface state, which couples to an adjacent ferromagnetic layer, leading to a spin-transfer torque. This torque is related to the Rashba-Edelstein effect in non-topological materials but with a different sign and larger magnitude due to the helical spin-momentum locking in the TI surface state. The experiments were conducted using spin-torque ferromagnetic resonance (ST-FMR) measurements on Bi₂Se₃/Py bilayers, where Py is a ferromagnetic material. The results show that the torque components in the in-plane and perpendicular directions are significant, with values of τ∥ = (2.7 ± 0.3) × 10⁻⁵ T and τ⊥ = (3.7 ± 0.4) × 10⁻⁵ T. The effective spin current conductivities σS,∥ and σS,⊥ were found to be comparable to those of the most efficient spin current sources, such as heavy metals. The spin torque angle θ∥, which is a key figure of merit for magnetic memory and logic applications, was found to be large, indicating that Bi₂Se₃ can provide very efficient electrical manipulation of magnetic materials at room temperature. The study also discusses the potential applications of Bi₂Se₃ in magnetic memory and logic devices, emphasizing the need to couple TIs to insulating or high-resistivity magnets to maximize the current flowing through the TI and minimize the contribution from the metallic magnet. The results suggest that TIs could enable new strategies for low-power, nonvolatile magnetic memory and logic structures, leveraging their room-temperature spin torque capabilities. The findings are supported by theoretical models that consider non-equilibrium spin accumulation near the TI surface and its diffusion into the ferromagnetic layer. The results highlight the potential of TIs as efficient spin torque sources for future magnetic device applications.This study reports the generation of a strong spin-transfer torque (STT) in a topological insulator (TI) thin film, Bi₂Se₃, when an in-plane current flows through it. The torque is directed in a manner consistent with the helical spin-momentum locking of the TI surface state. The results show that the strength of the torque per unit charge current density in Bi₂Se₃ is greater than that of any previously measured spin-torque source, even in non-ideal TI films where surface states coexist with bulk conduction. The mechanism involves the spin accumulation generated by the TI surface state, which couples to an adjacent ferromagnetic layer, leading to a spin-transfer torque. This torque is related to the Rashba-Edelstein effect in non-topological materials but with a different sign and larger magnitude due to the helical spin-momentum locking in the TI surface state. The experiments were conducted using spin-torque ferromagnetic resonance (ST-FMR) measurements on Bi₂Se₃/Py bilayers, where Py is a ferromagnetic material. The results show that the torque components in the in-plane and perpendicular directions are significant, with values of τ∥ = (2.7 ± 0.3) × 10⁻⁵ T and τ⊥ = (3.7 ± 0.4) × 10⁻⁵ T. The effective spin current conductivities σS,∥ and σS,⊥ were found to be comparable to those of the most efficient spin current sources, such as heavy metals. The spin torque angle θ∥, which is a key figure of merit for magnetic memory and logic applications, was found to be large, indicating that Bi₂Se₃ can provide very efficient electrical manipulation of magnetic materials at room temperature. The study also discusses the potential applications of Bi₂Se₃ in magnetic memory and logic devices, emphasizing the need to couple TIs to insulating or high-resistivity magnets to maximize the current flowing through the TI and minimize the contribution from the metallic magnet. The results suggest that TIs could enable new strategies for low-power, nonvolatile magnetic memory and logic structures, leveraging their room-temperature spin torque capabilities. The findings are supported by theoretical models that consider non-equilibrium spin accumulation near the TI surface and its diffusion into the ferromagnetic layer. The results highlight the potential of TIs as efficient spin torque sources for future magnetic device applications.