This study aimed to investigate the effects of the proportion of konjac in a blend of konjac and secondary gum (κcarrageenan and xanthan) from 25:75 to 50:50 and the levels of sweeteners (sucrose at 220% (w/v) and erythritolsucralose at 0.22.5% (w/v)) on the firmness of konjac gels using response surface methodology. The variation in the proportion of konjac greatly affected the gel firmness with respect to the sweetener. Increasing the konjac proportion increased the firmness of the konjac gels that were cogelated with either of the secondary gums. At a high konjac proportion, an addition of 211% sucrose increased the firmness of the konjac/κcarrageenan gel but decreased that of the konjac/xanthan gel. The addition of erythritolsucralose had a small effect on the konjac gel firmness. Predicted models of konjac gels were reliable and can be used to optimize the conditions that provided the greatest firmness. The optimal conditions were found to use the konjac/secondary gum at approximately 50:50 with 17% sucrose or 2.5% erythritolsucralose for the konjac/κcarrageenangel and with 2% sucrose or 0.76% erythritolsucralosefor the konjac/xanthan gel.