This study aims to investigate the clinical performance and the survival time of pulp-treated primary molars followed by high viscosity glass ionomer (HVGIC) restoration. A total of 39 children with a total of 42 primary molars that needed to receive pulp therapy were included. All pulp-treated primary molars were immediately restored with HVGIC restoration (Fuji IX GP EXTRA^TM) and evaluated using the modified Ryge’s criteria. The prepared cavities of studied teeth were classified into two groups, the cavities that did not extend beyond the line angles and cavities that extend beyond line angles were defined as the ideal-cavity and the less ideal-cavity restorations, respectively. The overall success rates of the studied teeth at baseline, 6-month, and 12-month follow-up periods were 97.6%, 97.6%, and 90.5% respectively. The overall success rate was statistically different between baseline and 12-month follow-up period (p=0.018), using Friedman’s test.         At a 12-month follow-up period, the success rate of ideal-cavity restoration was statistically higher than less-ideal cavity restorations (p=0.035), using Fisher’s exact test. A statistically significant difference, regarding marginal integrity, were found between both groups (p=0.035) while the difference in tooth integrity was not found between both groups (p=0.084). Secondary caries were not found in all studied teeth. The mean survival time for the ideal cavity group and less-ideal cavity group was 12 months and 11.6 months, respectively, using Kaplan-Meier analysis. The results after 1 year suggest that the HVGIC may be recommended as an alternative for restoring pulp-treated primary molar when a stainless steel crown is not indicated.