<p>Laparoscopic liver resection (LLR) is widely accepted; however, no prospective study has identified risk factors for conversion to open surgery. This multicenter prospective study aimed to identify risk factors for conversion to hand-assisted laparoscopic surgery or open liver resection and evaluate the impact of conversion on perioperative outcomes in LLR. From June 2020 to May 2024, patients scheduled for wedge resection or left lateral segmentectomy for solitary liver tumor &lt; 5&#xa0;cm were enrolled across seven institutions. A laparoscopic approach was employed for all patients. The primary endpoint was the identification of risk factors for conversion. As secondary endpoints, we compared perioperative outcomes between LLR and conversion. Among 199 patients, 172 (86.4%) completed LLR, while 27 (13.6%) required conversion. Multivariate analysis identified third or subsequent liver resection (<i>P</i> &lt; 0.001) and male sex (<i>P</i> = 0.029) as significant risk factors for conversion. Conversion was significantly associated with longer operative time (<i>P</i> = 0.001), greater blood loss (<i>P</i> &lt; 0.001), decreased implementation of the Pringle maneuver (<i>P</i> = 0.013), and prolonged hospital stay (<i>P</i> = 0.001). These findings highlight that conversion negatively impacts short-term outcomes. Awareness of these risk factors may support better surgical planning and risk stratification for patients undergoing LLR.</p>