The study scrutinized MHD and dissipated (SWCNTs-Fe3O4)/C2H6O2 hybrid Casson nanofluids flow over an unsteady stretchable rotating disk with a Cattaneo-Christov heat flux model. By means of proper similarity conversion, the boundary layer flow governing PDEs was changed into systems of dimensionless coupled nonlinear ordinary differential equations. Subsequently, the consequent nonlinear momentum and energy equations with their boundary conditions were worked out numerically employing the spectral quasilinearization method (SQLM). The convergence, stability, and accuracy of the SQLM were established as a computationally efficient method to solve a coupled system of boundary layer problems. It is specified that 5% of SWCNTs, 20% of Fe3O4, and 75% of C2H6O2 being taken for the preparation of (SWCNTs−Fe3O4)/C2H6O2 hybrid nanofluid with shape factor n1 = n2 = 3, and the values of the parameters used are fixed to M = 5, S = 0.5, β = 5, κ = 0.5, Ec = 2, Λ = 2, Pr = 7.3, α = 0.5, δ = 0. The effects of more perceptible parameters on velocity and thermal flow fields were considered and scrutinized carefully via graphs and tables. The results disclose that the momentum and thermal boundary layer thickness markedly declined with more value of the unsteady parameter. The local heat transfer rate improves nearly by 14% as 0.2 volume of Fe3O4 nanoparticles dispersed in 0.05 volume of SWCNTs and 0.75 volume of C2H6O2 nanofluid, hence, in realistic uses adding more values of nanoparticles in the hybrid nanofluids is useful to progress the heating process. The study is novel since to the best of the author’s knowledge, no paper has been published so far on the unsteady flow of (SWNT-Fe3O4)-Ethylene glycol hybrid Casson nanofluid with the effects of the Cattaneo-Christov heat flux model. As well, the model used for the thermophysical properties of the hybrid nanofluid is a new approach. Generally, hybrid nanofluids of (SWCNTs-Fe3O4)/C2H6O2 show better flow distributions with good stability of thermal properties than their mono counterparts.