Introduction: The introduction of radial-firing laser fibers has minimized catheter-to-vein distance during endovenous laser ablation (EVLA) for the great saphenous vein (GSV) and anterior saphenous veins (ASVs). This study investigates flush endovenous laser ablation (fEVLA) effectiveness in addressing chronic superficial venous insufficiency (CVI). Materials and methods: This single-center retrospective study analyzed consecutive fEVLA cases with duplex ultrasound follow-up at 1, 4, and 12 weeks. The primary endpoint was clinically significant endovenous heat-induced thrombosis (classes III–IV). Results: Three hundred and twelve patients were recruited (405 affected limbs, 369 GSV, and 36 ASV). CEAP classifications were stratified as follows: C2 in 6.1%, C3 in 34.2%, C4 in 44%, C5 in 2.7%, and C6 in 12.7% of cases. Perforator ligation, phlebectomy, or foam sclerotherapy were carried out in conjunction with EVLA. fEVLA was feasible in all cases. The success rate was 96.78%, defined as EHIT classes 1 and 2, and assessed by ultrasound one week postoperatively. Clinically significant EHIT (2.5% class 3 and 0.2% class 4) was managed with 15 mg rivaroxaban twice daily for 21 days. Follow-up at 4 weeks revealed complete resolution of all EHIT 3–4 cases. No cases of pulmonary embolism or deep vein thrombosis were observed during the study or follow-up period. Conclusions: fEVLA is a safe treatment for superficial CVI across various CEAP classes, and with prompt detection, the minimal complication rate can be completely resolved.