A millimeter-scale magnetic steering continuum robot is introduced for transluminal procedures, enabling apical extension while maintaining structural stability. The robot uses phase transition components to execute tip-based elongation cycles, steered by programmable magnetic fields. Each motion cycle features a solid-like backbone for stability and a liquid-like component for advancement, allowing autonomous shaping without environmental interactions. Combined with clinical imaging technologies, the robot can navigate through tortuous and fragile lumina to transport microsurgical tools. Once reaching larger anatomical spaces, it can morph into functional 3D structures for surgical or sensing tasks. The robot's design allows for enhanced safety, multi-functionality, and cooperative capabilities among millimeter-scale continuum robots, opening new avenues for transluminal robotic surgery. The robot's working principle involves alternating phase transition components (PTCs) that move axially relative to each other. The PTCs can transition between solid and liquid states, altering stiffness to switch roles between support and movement. The Guider, heated to a phase transition temperature, becomes flexible for forward movement, while the Follower remains rigid to provide support. The robot's motion cycle alternates between these states, allowing it to navigate through complex environments. The robot's thermal management system ensures efficient heating and cooling, with the PTCs' temperatures controlled to maintain structural integrity. The robot's periodic numerical control enables deployment along planned paths, with the Guider first heated to flexibility, then propelled forward by the advancement unit and steered by the magnetic field. The Follower is then heated to flexibility and advanced along the Guider's trajectory. The robot's ability to form functional structures in situ, such as hooks, lassos, and knots, expands its surgical applications. The robot's biocompatibility and clinical safety have been validated through in vitro and in vivo experiments, demonstrating its potential for medical applications. The robot's integration with imaging technologies, such as ultrasound and X-ray, enhances its navigation capabilities and clinical utility. Future developments aim to improve the robot's performance, miniaturization, and integration with existing medical technologies for broader applications in transluminal robotic surgery.A millimeter-scale magnetic steering continuum robot is introduced for transluminal procedures, enabling apical extension while maintaining structural stability. The robot uses phase transition components to execute tip-based elongation cycles, steered by programmable magnetic fields. Each motion cycle features a solid-like backbone for stability and a liquid-like component for advancement, allowing autonomous shaping without environmental interactions. Combined with clinical imaging technologies, the robot can navigate through tortuous and fragile lumina to transport microsurgical tools. Once reaching larger anatomical spaces, it can morph into functional 3D structures for surgical or sensing tasks. The robot's design allows for enhanced safety, multi-functionality, and cooperative capabilities among millimeter-scale continuum robots, opening new avenues for transluminal robotic surgery. The robot's working principle involves alternating phase transition components (PTCs) that move axially relative to each other. The PTCs can transition between solid and liquid states, altering stiffness to switch roles between support and movement. The Guider, heated to a phase transition temperature, becomes flexible for forward movement, while the Follower remains rigid to provide support. The robot's motion cycle alternates between these states, allowing it to navigate through complex environments. The robot's thermal management system ensures efficient heating and cooling, with the PTCs' temperatures controlled to maintain structural integrity. The robot's periodic numerical control enables deployment along planned paths, with the Guider first heated to flexibility, then propelled forward by the advancement unit and steered by the magnetic field. The Follower is then heated to flexibility and advanced along the Guider's trajectory. The robot's ability to form functional structures in situ, such as hooks, lassos, and knots, expands its surgical applications. The robot's biocompatibility and clinical safety have been validated through in vitro and in vivo experiments, demonstrating its potential for medical applications. The robot's integration with imaging technologies, such as ultrasound and X-ray, enhances its navigation capabilities and clinical utility. Future developments aim to improve the robot's performance, miniaturization, and integration with existing medical technologies for broader applications in transluminal robotic surgery.