At-home testing facilitates early screening and longitudinal monitoring of immune disorders, significantly enhancing patient engagement in personalized healthcare management. This convenient self-testing capability primarily stems from advancements in microfluidic technology, with the microfluidic chain reaction (MCR) demonstrating particular efficacy. MCR platforms incorporate self-regulating flow control that streamlines analytical workflows into intuitive, single-activation processes. Nevertheless, current MCR platforms still face challenges in achieving self-contained, precise, and multiplexed fluid control without external instrumentation or pretreatment, which restricts their broad applicability. Here, we present a self-powered gravity domino microfluidics (SGDM) featuring multimode fluid modulation for at-home immunoassays. It streamlines fluid control to a single-flip operation while ensuring precise, sequential reagent release through negative-pressure modulation. The self-adjustable microfluidic channels enable tunable flow resistance control, permitting spatiotemporally programmable reagent distribution with improved versatility. In performance validation, SGDM demonstrates successful immunoassays, with 45 min of antinuclear antibody profiling for endogenous autoimmune disorders and 90 min of allergen screening for exogenous hypersensitivity reactions. Additionally, clinical validation studies demonstrate 99.61% accuracy for antinuclear antibody detection and 98.99% accuracy for allergen identification. This high performance was further validated by a multicenter study that yielded consistent accuracies of 98.61%, 99.48%, and 99.17% across three independent clinical centers. To further enhance reliability, a deep-learning model has been implemented for automated signal analysis, eliminating human variability while maintaining over 98% accuracy. Together, SGDM enables at-home immunoassays by integrating self-powered gravity-driven flow control with AI-powered analysis, enabling precise, user-friendly testing with high accuracy through a simple single-flip operation.