Informalized employment persists and emerges in new forms in advanced and developing economies although it often coincides with precariousness, unfair competition, and loss of revenues and state legitimacy. To investigate the mechanisms of such persistence this thesis builds an extended structuralist approach that combines Global Production Networks (GPNs) studies and Labour Process Theory (LPT). This approach reframes informalization as a tool of labour control and posits that informalization - while influenced by structural economic pressures and local socio-institutional contexts - is ultimately shaped by the employer-employee relations in the workplace. The thesis adopts the footwear-garment GPNs in (Southern) Italy and Albania as a typical case study to analyse the informality persistence within globalized production processes. The research relies on an extended case method and a multi-sited, qualitative fieldwork based on interviews and focus groups with workers, unionists, managers, labour inspectors, NGO representatives, policymakers, and other stakeholders. Firstly, through an analysis of recent anti-informality policies in the two countries, the thesis highlights the economic and political costs of eradicating informal employment. In both countries, policies lead to a low-compliance-equilibrium that partially steer informalization practices from full to partial informality without however eliminating widespread irregularities. Secondly, the research analyses the differentiated informalization dynamics that emerge within the garment-footwear GPNs and shows how these are primarily used by firms to cut labour costs and enhance workers' disposability. At the same time, informalized employment is shaped by workers and persists only as long as they are unable or unwilling to resist it. The thesis explains the differentiated informalized labour regimes that emerge in GPNs as the combination of three variables: firms' position in the chain and the competitive pressures they face, the associational power of workers, and the level of workers' replaceability due to the specific skills required by the labour process of each firm and the local labour supply.