This paper introduces a millimeter-scale magnetic steering continuum robot designed for transluminal procedures. The robot features a dual-component system based on phase transitions, enabling tip-based elongation and accurate steering through programmable magnetic fields. Each motion cycle includes a solid-like backbone for stability and a liquid-like component for advancement, allowing the robot to be shaped autonomously without relying on environmental interactions. The robot can navigate through tortuous and fragile lumina, reducing tissue damage and friction. Once it reaches larger anatomical spaces, it can transform into functional 3D structures, such as surgical tools or sensing units, overcoming the limitations of narrow pathways. The robot's capabilities are demonstrated through ex vivo and in vivo studies, showing its mobility, functionalities, and compatibility with existing medical technologies. The design enhances safety, multi-functionality, and cooperative capabilities, opening new avenues for transluminal robotic surgery.This paper introduces a millimeter-scale magnetic steering continuum robot designed for transluminal procedures. The robot features a dual-component system based on phase transitions, enabling tip-based elongation and accurate steering through programmable magnetic fields. Each motion cycle includes a solid-like backbone for stability and a liquid-like component for advancement, allowing the robot to be shaped autonomously without relying on environmental interactions. The robot can navigate through tortuous and fragile lumina, reducing tissue damage and friction. Once it reaches larger anatomical spaces, it can transform into functional 3D structures, such as surgical tools or sensing units, overcoming the limitations of narrow pathways. The robot's capabilities are demonstrated through ex vivo and in vivo studies, showing its mobility, functionalities, and compatibility with existing medical technologies. The design enhances safety, multi-functionality, and cooperative capabilities, opening new avenues for transluminal robotic surgery.