This study proposes a model to explore how inconsistencies in emoji usage (exaggeration, misapplication, and excessive use) affect recipients' cognition and emotions. It also examines the relationship between users' emoji knowledge and their emotions and cognition, following the cognitive dissonance process model (CDPM). Through structural equation modelling and a sample of 400 participants, a questionnaire survey was conducted. The findings reveal key insights: inconsistent emoji usage relates positively to feelings of dissonance, emphasising the importance of context-appropriate emoji use for clear communication. Dissonance connects to unpleasant arousal, indicating that emoji-related cognitive dissonance can lead to negative emotional responses, potentially impacting communication quality. Additionally, deeper emoji knowledge reduces usage inconsistencies but does not directly affect dissonance, highlighting its complex nature. These findings offer recommendations for improving emoji usage and digital communication practices.