Background To evaluate the efficacy and safety of pharmacomechanical thrombectomy using a new rotational thrombectomy device with additional thrombus-removal methods for deep venous thrombosis. Methods A total of 91 patients admitted to our tertiary center with symptomatic iliac, ilio-femoral, femoro-popliteal deep venous thrombosis and who underwent hybrid pharmacomechanical thrombectomy constituted the study group. Postinterventional color Doppler ultrasonography was repeated at 1st, 6th, and 12th months. Villalta scoring system was used to evaluate the patients for the development of post-thrombotic syndrome after deep venous thrombosis. The patient-reported severity of pain in the index leg was measured on a Likert scale. Results Of the 91 patients whose charts were reviewed, the location of thrombus was iliofemoral in 60 (65.9%) and femoropopliteal in 31 (34.1%) patients, respectively. Duration of symptoms was 5.62 ± 3.43 (range, 2–15) days. Technical success was observed in 82 patients (90.1%) at 3 months, in 77 patients (84.6%) at 6 months, and in 74 patients (81.3%) at 12 months. Villalta score was over 10 points in 15 of 17 patients whose Doppler US revealed venous occlusions, at 12 months, and in 8 patients with recurrent deep venous thrombosis. Post-thrombotic syndrome was detected in 18 patients in our study. Twelve (13.2%) of these 18 patients had mild, 5 (5.5%) moderate, and 1 (1.1%) severe PTS. In predicting predisposing factors in 18 patients with PTS, 13 patients (72.2%) had a Villalta score ≥10, 10 patients (55.6%) had experienced a delayed endovascular procedure (≥10 days), and 8 patients (44.4%) had recurrent deep venous thrombosis. Conclusion The endovenous pharmacomechanical thrombectomy with the Mantis thrombectomy device in the treatment of acute and subacute iliofemoral deep venous thrombosis is a promising approach in terms of efficacy and safety in the early period regarding reasonable and long-term prevention of post-thrombotic syndrome, development of pulmonary thromboembolism, and adequate venous system patency.