The quality of teacher training is highly likely to influence the quality of learning outcomes. In this view, the present paper aimed to develop a pre-service teachers’ job readiness model integrating individual variables associated with teacher professionalism. The study followed an exploratory cross-sectional research design. A sample of 312 Romanian pre-service STEM (Science, Technology, Engineering, and Mathematics) teachers was selected based on availability criteria. A pre-tested self-administered questionnaire using a 5-point Likert scale was applied during the data collection process. Data analysis was based on a combination of descriptive and inferential statistics, a blending factor analysis and structural equations modeling. A conceptual model of teaching readiness from the teacher professionalism perspective was developed and tested using empirical data. The results suggest that professional knowledge, professional practice, professional engagement and self-management could be considered central dimensions of teacher professionalism, being highly relevant in assessing pre-service teacher job readiness. Moreover, professional knowledge has a strong and positive influence on teaching practice and professional engagement. In relation to the professional knowledge latent variable, the ability to conduct didactic transposition is the most influential. Following the same line of analysis, the most significant vectors of the professional practice variable were found to be the ability to design effective evaluation tools and to analyze and interpret learning outcomes. The research revealed the presence of vulnerable or sensitive areas of teacher training that could be a result of curriculum design. With respect to managing disruptive behaviours, the customization of learning and emotional self-regulation are considered weak areas of teaching readiness. The results could be useful for policymakers and teacher training practitioners in order to improve overall job readiness and teacher professionalism.