Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an effective treatment for Parkinson's disease (PD), yet individual motor outcome remains insufficiently predictable. The effect of DBS depends on modulating brain networks, and this study evaluates whether targeting using patient-specific connectivity with 7-Tesla (7T) MRI probabilistic tractography enhances motor outcome. For connectivity analysis, selective visualization of STN connectivity to the primary cortical motor areas was performed before surgery, and electrode lead placement was directed at the connectivity-derived motor subdivision of the STN. Motor outcome, measured using the Movement Disorders Society Unified Parkinson Disease Rating Scale motor part (MDS-UPDRS part III), of 102 PD-DBS patients for whom 7T MRI connectivity analysis was used for DBS targeting, was compared to a matched control group of 118 PD-DBS patients for whom 7T MRI T2-weighted classical anatomical landmarks were used for targeting. Results of this prospective comparison show that patients operated with connectivity-guided targeting showed significantly more motor improvement compared to the control group: 56 ± 15% vs. 50 ± 20% (p = 0.015), and the connectivity-guided group showed a higher optimal response rate (96% vs. 86%, p = 0.008). Connectivity analysis enabled localization of DBS electrodes in reference to the motor subdivision. The leads that were optimally located inside the motor subdivision showed an average of 60 ± 11% motor improvement. Our findings demonstrate the clinical applicability of 7T MRI probabilistic tractography for visualizing connectivity between the STN and cortical motor areas to enable electrode lead placement directed at the motor subdivision of the STN, introducing patient-specific connectivity analysis guided DBS. This proved to be an individual biomarker for implantation location that increased the effectiveness of DBS in patients with PD.