Biomolecular condensates mediate diverse and essential cellular functions by compartmentalizing biochemical pathways. Many condensates have internal subdomains with distinct compositional identities. A major challenge lies in dissecting the multicomponent logic that relates biomolecular features to emergent condensate organization. Nuclear paraspeckles are paradigmatic examples of multi-domain condensates, comprising core and shell layers with distinct compositions that are scaffolded by the lncRNA NEAT1, which spans both layers. A prevailing model of paraspeckle assembly proposes that core proteins bind directly and specifically to core-associated NEAT1 domains. Combining informatics and biochemistry, we unexpectedly find that the essential core proteins FUS and NONO bind and condense preferentially with shell-associated NEAT1 domains. The shell protein TDP-43 exhibits similar NEAT1 domain preferences on its own but forms surfactant-like shell layers around core protein-driven condensates when both are present. Together, experiments and physics-based simulations suggest that competitive RNA binding and immiscibility between core and shell proteins orders paraspeckle layers. More generally, we propose that sub-condensate organization can spontaneously arise from a balance of collaborative and competitive protein binding to the same domains of a lncRNA.The cellular milieu is spatially organized into compartments called biomolecular condensates that exhibit rich internal organization which shapes their functions. Often comprising multiple proteins and RNAs, a major question concerns how molecular-scale features relate to emergent condensate forms. Here we study nuclear paraspeckles, archetypal multi-domain condensates comprising distinct core and shell layers assembled around a layer-spanning RNA scaffold. We find that different proteins associated with each layer all bind preferentially to the same shell-associated domains of the RNA scaffold. Core and shell proteins are inherently immiscible, establishing a competition that redirects core proteins to a suboptimal, core-associated domain of the scaffold. Our work reveals how a combination of competitive RNA binding and protein immiscibility can spatially organize multicomponent condensate subdomains.