Explicitly attending to justice in science teaching and learning is long overdue. Here, we examined the professional teacher identity development of 13 science teachers as they collaborated in networked professional learning communities (PLCs) to implement and revise a culture-setting unit focused on the science of COVID and engaging in collaborative inquiry cycles to identify and refine justice-centered ambitious science teaching (JuST) practices in classrooms. These JuST practices are conceptualized as a synthesis of justice-centered pedagogies and ambitious science teaching. To accomplish our research aims, we drew on qualitative methods, where we relied on transcribed video recordings of 21 PLC meetings and three transcribed end-of-year focus group interviews of two PLCs (i.e., 13 secondary science teachers, mostly white) across a year-long period. As a result of our analyses, we identified how professional learning arranged through PLCs, culture-setting units, and collaborative inquiries supported professional JuST identity development by, among other affordances, providing space for the critical and emotional work of learning to discuss race, affording teachers strategies for getting to know their students and the assets they bring to classrooms, and recognition and positioning of teachers as professionals capable of identifying or developing, refining, and contributing to knowledge about JuST science teaching and learning. Challenges identified included, among others, identifying how the culture-setting units could be effectively integrated into existing curriculum maps and the uneven implementation support from administrators. In the end, what is revealed helps better conceptualize how engaging teachers in PLCs around tasks like curriculum implementation and refinement or collaborative inquires support professional JuST identity development and how such experiences can be more carefully negotiated.