This study reports the development of twisted single-walled carbon nanotube (SWCNT) ropes with exceptional nanomechanical energy storage capacity. The twisted ropes, wrapped in thermoplastic polyurethane (TPU), demonstrate a gravimetric energy density of up to 2.1 MJ kg⁻¹, surpassing mechanical springs by four orders of magnitude and lithium-ion batteries by a factor of three. The energy is safe, non-depleting, and accessible across a wide temperature range (-60 to +100 °C). The ropes exhibit high energy recovery efficiency, with nearly complete energy recovery after 100 cycles. The energy storage is achieved through the twisting of SWCNTs, which store mechanical energy in multiple channels, including stretching, twisting, compression, and bending. The energy is released rapidly and efficiently, with a power density of up to 1.85 MW kg⁻¹. The twisted ropes show excellent stability and can be used in various applications, including energy storage in compact devices and medical implants. The study highlights the potential of SWCNT ropes as a safe, efficient, and high-capacity energy storage solution, with promising applications in energy systems and medical devices. The results demonstrate that twisted SWCNT ropes can store and release mechanical energy with high efficiency, offering a new approach to energy storage that is both safe and environmentally compatible.This study reports the development of twisted single-walled carbon nanotube (SWCNT) ropes with exceptional nanomechanical energy storage capacity. The twisted ropes, wrapped in thermoplastic polyurethane (TPU), demonstrate a gravimetric energy density of up to 2.1 MJ kg⁻¹, surpassing mechanical springs by four orders of magnitude and lithium-ion batteries by a factor of three. The energy is safe, non-depleting, and accessible across a wide temperature range (-60 to +100 °C). The ropes exhibit high energy recovery efficiency, with nearly complete energy recovery after 100 cycles. The energy storage is achieved through the twisting of SWCNTs, which store mechanical energy in multiple channels, including stretching, twisting, compression, and bending. The energy is released rapidly and efficiently, with a power density of up to 1.85 MW kg⁻¹. The twisted ropes show excellent stability and can be used in various applications, including energy storage in compact devices and medical implants. The study highlights the potential of SWCNT ropes as a safe, efficient, and high-capacity energy storage solution, with promising applications in energy systems and medical devices. The results demonstrate that twisted SWCNT ropes can store and release mechanical energy with high efficiency, offering a new approach to energy storage that is both safe and environmentally compatible.