In this paper, we present a fully soft miniaturized continuum robot that integrates 3D optical shape sensing through functionalized tubing used as soft optical waveguides. The sensor is fabricated by laser patterning an off-the-shelf medical tubing, allowing for bidirectional responses to large curvatures in two bending directions, enabling 3D shape sensing and tip tracking of the continuum robot. The robot is able to bend and sense its own shape up to a curvature of 44.7 m-1, corresponding to a bending angle of 102°, having high-accuracy tracking capabilities, resulting in an average tracking error of 3.08 mm, that is 7.7 % of the robot length. The robot’s functionality was shown in validation experiments, including a real-time shape prediction through a graphical user interface.