The study explored the impact of work-integrated learning on shaping the professional identities of Postgraduate Certificate in Education (PGCE) pre-service teachers at a university in South Africa. The research employed a qualitative case study approach where data was generated using a semi-structured interview protocol with 26 PGCE pre-service teachers, 14 females and 12 males, that were purposively selected as the study sample. Data generated through the semi-structured interviews was analysed using thematic method. The study is framed using the Personal Construct Theory (PCT). According to the theory, constructs (professional identities) are drawn from the experiences and perceptions of individuals about a specific exercise, in this case, teaching practice. Thus, the application of PCT in the teaching practice exercise revealed that Work Integrated Learning (WIL) aided PGCE pre-service teachers in articulating the various constructs experienced during the WIL as it exposed them to mentor teachers and other staff members' support. According to the findings, such exposure resulted in the development of professional identities in pedagogical knowledge, inclusive education strategy, classroom management and communication skills, and collaborative and administrative skills. Thus, it is concluded that the condition of the school environment can impact preservice teachers' development of professional identities. Based on the conclusion, recommendations were made, which include, among others, the need for robust collaboration between teacher training institutions (universities) and partner schools to ensure every member understands their role in providing the needed support for pre-service teachers at their respective learning sites and the need for the capacity building of mentors in schools who guide the pre-service teachers on a daily basis during teaching practice.