This research aimed at improving primary pupils' grammar learning in order to increase their grammar achievement by discovering the grammatical language features as well as motivating them to gasp the grammar content accurately and practice its tedious tasks with fun. Grammar rules and practice drills of units six and seven in the Ministry of Education second term English Language Textbook for 6th primary grade (Time for English 6) were introduced to the experimental group in the form of guided discovery based gamified tasks in order to determine how far guided discovery based gamification was effective in improving their grammar learning. The participants were 64 6th year primary grade pupils from one of Ismailia public governmental primary schools. The research design was the experimental one in which the participants were divided into two groups: Experimental group of 32 pupils and Control group of 32 pupils. The measurement tool was a grammar test developed by the researcher. The findings revealed that discovery based gamified tasks improved primary pupils' grammar learning significantly. So, they are recommended to be