Nowadays, software development companies use agile methodologies to increase the speed and flexibility required by unpredictable working environments and streamline the software delivery process. Agile methodologies emphasize the software engineers’ interactions rather than rigid software development processes. Therefore, agile software development processes (e.g., implementing user stories) should consider software engineers’ affective states since these influence agile software project activities (e.g., team composition or decision-making). We conducted a systematic mapping review following the guidelines of Petersen, K. and Kitchenham, B. to answer our research question: “What affective states influence agile software engineers’ performance and developed software quality?”. We retrieved over 16,000 articles published between January 2010 and September 2021 and after applying selection criteria, 24 primary articles were identified. The results show that the affective states of software engineers influence the activities of the software project and the software development process. Furthermore, we found that there is a lack of well-defined and standard metrics to study the influence of software engineers’ affective states on their performance and the quality of the resulting software. Finally, we concluded that studying and understanding the affective states of software engineers in agile environments is crucial to achieve their well-being at work and improve their performance. •Metrics to measure performance should include the software engineer’ affective states.•The affective data collection methods most used in the agile literature are intrusive.•Most of the affective states reported in the agile literature are negative.•Agile software engineers’ affective states influence agile software project activities.•Agile Engineering does not have well-defined performance metrics considering emotions.