Education institutions globally, are increasingly driven to integrate innovative technologies in teaching spaces. While many studies have been conducted on e-learning, blended learning and m-learning, only a few studies have concentrated on the STEM preservice teachers' e-readiness for using online multimodal teaching methods in developing economic contexts. Therefore, the purpose of this paper is to examine the interplay of experiences, attitudes and technological pedagogical content knowledge (TPACK) self-efficacy as they influence STEM preservice teachers' e-readiness for implementing online multimodal teaching. This paper employed a descriptive online survey method and a stratified random sampling technique to collect data from 204 final-year STEM preservice teachers on a teacher training programme in South Africa. Statistical tools of confirmatory factor analysis, exploratory factor analysis, bivariate and correlation analysis were employed on the collected data. The results revealed that STEM preservice teachers have positive attitudes towards multimodal online learning. However, STEM preservice teachers do not feel confident in using multimodal online resources in their teaching. In addition, this paper found that experiences of online multimodal teaching impacted on preservice teachers' attitudes and resultantly, STEM preservice teachers' TPACK self-efficacy. The results and discussions inform the design for improvement in online multimodal teaching methods e-readiness and usage by preservice teachers. Recommendations include resource support, alignment of teacher training curricula and development of practicum practices for overall improvement of preservice teachers' experiences.