Carbon nanotube field-effect transistors (CNFETs) require the formation of large-area, densely packed, and uniformly aligned carbon nanotube (CNT) monolayers to achieve high device performance. Although solution-based assembly has attracted significant attention as a promising route for large-area fabrication, the self-assembly behavior of CNTs in liquid environments is extremely challenging to probe experimentally. Consequently, the physicochemical mechanisms governing CNT accumulation and alignment at liquid–liquid interfaces remain poorly understood. In this work, we investigate CNT self-assembly at immiscible liquid–liquid interfaces using multiscale simulations that integrate atomistic molecular dynamics (MD) and mesoscale dissipative particle dynamics (DPD). Molecular-scale thermodynamic inputs obtained from atomistic MD simulations, specifically Hildebrand solubility parameters, are utilized to calculate the repulsion parameters in the mesoscale DPD model. DPD simulations reveal that CNTs preferentially localize at liquid–liquid interfaces and progressively accumulate over time, leading to spontaneous self-assembly and a transition toward liquid-crystal-like ordered states. Systematic parametric studies further demonstrate that the degree of ordering is strongly governed by interfacial miscibility, CNT–solvent affinity, and interfacial CNT concentration, highlighting their decisive roles in controlling CNT alignment at liquid interfaces. These results elucidate the physical mechanisms governing CNT alignment at complex liquid–liquid interfaces and are expected to serve as practical design rules for the rational development of large-area, solution-based CNT monolayer fabrication processes for CNFET applications.