This study investigates how perceived job insecurity shapes trade union membership within a South African Higher Education Institution (HEI), with a specific emphasis on the role of gender. Drawing on Psychological Contract Theory and Social Exchange Theory, the study examines how gendered experiences of work influence feelings of insecurity, perceptions of fairness, and employees’ reasons for seeking union protection. A qualitative research design was adopted to explore employees’ lived experiences. Semi-structured interviews were conducted with eight participants, four females and four males, across both permanent and contract job categories. Data were analysed thematically to identify gendered patterns in job insecurity, psychological contract breach, and motivations for joining trade unions. The findings show that job insecurity is deeply gendered. Female participants consistently reported greater vulnerability, even when occupying permanent positions. They described higher levels of uncertainty, heightened awareness of organisational restructuring, and increased exposure to unfair or unilateral managerial decisions. These experiences intensified feelings of psychological contract breach and eroded trust in the employer. Consequently, women were more likely to view the trade union as an essential source of protection, advocacy, and stability. Male participants acknowledged insecurity but perceived it as less personally threatening, resulting in weaker pressure to join or rely on unions. The study concludes that gender significantly shapes how job insecurity is experienced and how employees respond to it. Women’s heightened sense of vulnerability strengthens the pathway between job insecurity and trade union membership. These findings highlight the need for gender-responsive organisational practices and reinforce the vital role of unions in safeguarding those who feel disproportionately insecure in the workplace.