Boccia is a fun and stimulating physical active sport suitable for people with Cerebral Palsy (CP). The Boccia class three (BC3) players include those with four-limbs-motor-dysfunction with or without CP. These players can request a sport assistant that may help them physically during the game but not in their game strategy. In this work we investigated the use of a supplementary communication sportive board constructed specifically to improve the interaction of Paralympic BC3 players with their sport assistants. This case study enrolled a two-year-experience-CP-BC3 athlete with classification of gross motor function at level 5, severe four limbs dysfunction, low strength and coordination, and no verbal/oral language use but small body movements. This study was performed in a sport club during one month of training, twice a week for two-hour sessions. The sportive communication board (SCB) was designed based on Boccia rules and symbols using white and colored papers, scissors and glue. In the first two training sessions, the Paralympic athlete did not use the sportive board, whereas in the other two sessions the board was tested and the performance was compared. A set of questionnaires was applied to the legal tutor and the sport assistants before and after the SCB tests together with the analysis of the recording of a training session. According to our questionnaires data analysis, a significant contribution to the assistant understanding of the athlete game strategy was noticed by the legal tutor and the sport assistants when using the SCB. Improvement on time playing (reduction of 22%) and difficulty imposed to the opponent (increase of 33%) were the most important data detected during the tests. According to our video-records, the use of the SCB generated positive effects on the athlete overall performance, improving their communication. In fact, after this study, the BC3 player―which was allowed to keep the sportive board―has always required SCB during her training sets, which reinforced our perception of this material applicability and contribution to the player performance. Thus, we suggest that this SCB may be adapted and more explored to the use in other sport activities helping other Paralympic athletes in their performances as well as other sport assistants in their work activities.