In the case of “hidden” T?joints, the non-visible web sheet is welded through the face sheet. Positioning tolerances and movement due to the distortion of the web sheet represent the main challenges for staying on track during laser beam welding. This study investigates the assumption that keyhole monitoring based on optical coherence tomography (OCT) can be utilized for seam tracking by detecting critical misalignments between the laser beam and the web sheet position. It hereby analyzes whether an emerging misalignment between the laser beam and the web sheet can be discerned in the OCT data before the laser beam misses the web sheet and penetrates only the face sheet without connection. To this end, this study investigates the welding of hidden T?joints with angular and parallel offsets of the laser path relative to the web sheet centerline while recording with OCT. The interface zone between the web and face sheets is recorded by a high-speed camera to detect the transmission of laser radiation through a lower keyhole opening. It is shown that a lower keyhole opening, in combination with transmitted radiation, is advantageous for the reliable detection of an emerging misalignment. When such a lower keyhole opening occurs prior to a misalignment, and therefore lateral to the web sheet, it becomes feasible to predict spot misalignments via OCT.