<p>This article reinterprets global migration governance through a revised world-systems lens, arguing that deterrence regimes increasingly operate through engineered semi-peripheries: spatial and institutional functions that absorb legal, reputational, and logistical burdens displaced by core states. These containment spaces are constructed through legal outsourcing, diplomatic framing, targeted transfers, fiscal substitution, institutional buffering, and interior enforcement, allowing states to preserve humanitarian legitimacy while externalising or internalising control. Drawing on cases from Europe, East and Southeast Asia, Australia, and the Americas—including UK–Rwanda, Italy–Albania, EU–Turkey, Australia’s offshore regime, Japan and South Korea’s fiscal substitution, U.S.–Mexico subcontracting, and U.S. interior enforcement—the article shows that migration governance functions as a deterrence-based modular system sustained by strategic ambiguity. It reconceptualises the semi-periphery as a contested governance site, expands externalisation beyond territorial delegation, and interprets institutional instability as a design feature of post-normative containment.</p>