Introduction: Early loss of deciduous teeth leads to deleterious effects on permanent dentition. Hence, pulpectomy is considered a viable option in the treatment of necrotic primary teeth. With the advent of technology, pediatric endodontics has also evolved leading to an evolutionary shift from a traditional hand filing system to a rotary system leading to quicker, economical, and sustainable root canal treatment outcomes. Aim: To compare root canal preparation and obturation time and to evaluate post-operative signs and symptoms following single sitting pulpectomy in primary mandibular molars using hand and rotary instrumentation in young children aged between 4-7 years. Materials and Methods: Pulpectomy was performed on 150 primary molars. Hand K files were used for half of them, while Pro AF baby gold rotary files were used for the other half randomly divided. The time utilized for instrumentation, the quality of obturation obtained, and post operative pain were noted. Results: In comparison to hand filing, it was found that Pro AF baby gold required less time for instrumentation and offered the best possible obturation. The post operative pain observed with Pro AF baby gold was significantly less than hand filing at 6 hrs and 12 hrs intervals. However, the follow-up at 24 hrs, 48 hrs, 72 hrs, 1 week, and 3 weeks depicted no significant difference between the two systems. Keywords: Pulpectomy, Primary Teeth, Hand K-files, Rotary files, Instrumentation, Obturation, Post-Operative Pain.