This theoretical study examines the effects of thermal radiation, viscous dissipation, and a magnetic field effect on a nanofluid that contains carbon nanotubes in blood and moves over a two-way expanding surface. We consider both the stretching and contracting directions when examining the bidirectional nature of the expanding surface. We define the problem’s governing equations, which include energy and momentum, and transform them into a set of ordinary differential equations using suitable similarity transformations. We semi-numerically solve the resulting equations using HAM methods and the BVPh. 2.0 program. We also discuss the consequences of heat radiation and viscosity dissipation in the nanofluid. The Rosseland approximation models the effect of thermal radiation, while the incorporation of fluid’s internal friction represents viscous dissipation. This research aims to investigate the combined effects of various parameters, such as thermal radiation, Eckert number, nanoparticle volume fraction, couple stress parameter, power law index, magnetic field, and Prandtl number, on the heat, flow, and transfer properties of single-walled carbon nanotube (SWCNT), multi-walled carbon nanotube (MWCNT), and blood-based nanofluids. A fascinating field of study, this study will reveal useful details about the possible uses of carbon nanotube blood-based nanofluids across bidirectional expanding surfaces in drug delivery systems, heat transfer processes, and biomedical engineering. Blood-based nanofluids can benefit from the inclusion of carbon nanotubes to improve fluid behavior and thermal conductivity, which is crucial for a number of industrial and medicinal applications.