<p>Using digital technologies in assessments has become a common practice among higher education teachers. This enriches the concept of teacher assessment literacy (AL), thus making it necessary to develop a new scale to measure higher education teachers’ AL in technology-assisted contexts. Therefore, this study applied Onwuegbuzie et al.’s (2010) instrument development and construct validation (IDCV) process as a mixed methods framework to develop and validate a new scale. In Phases 1 to 5, the scale was developed based on the framework generated from the literature review and focus group interviews. Phases 6 to 9 involve quantitative and qualitative data analyses, as well as crossover analyses based on a sample of <i>N</i> = 265 higher education teachers in China. In Phase 10, both the product and the process were evaluated to help the researcher reflect on the research and discover areas for further improvement. The scale developed and validated in this study encompasses two parts: assessment knowledge and assessment competence. Results demonstrated that assessment competence in technology-assisted contexts is not simply measured by a total score, but a dynamic system composed of nine closely collaborative and interactive professional practices. This instrument and the accompanying reflections offer valuable insights for future research on integrated approaches to developing AL among higher education teachers.</p>