This study presents a vortex-based soft magnetic composite (SMC) with ultrastable permeability up to gigahertz frequencies. The composite is fabricated using cold-sintering, where ultrafine FeSiAl particles are magnetically isolated and covalently bonded by an Al2SiO5/SiO2/Fe2(MoO4)3 multilayered heterostructure. This structure results in an ultrastable permeability of 13 up to 1 GHz, a relatively large saturation magnetization of 105 Am²/kg, and a low coercivity of 48 A/m. The ultimate compressive strength of the composite is also increased to 337.1 MPa due to the epitaxially grown interfaces between particles. The study deepens the understanding of magnetic vortices and provides an alternative concept for designing integrated magnetic devices, particularly for high-frequency applications such as inductors and transformers in more-than-Moore era integrated circuits.This study presents a vortex-based soft magnetic composite (SMC) with ultrastable permeability up to gigahertz frequencies. The composite is fabricated using cold-sintering, where ultrafine FeSiAl particles are magnetically isolated and covalently bonded by an Al2SiO5/SiO2/Fe2(MoO4)3 multilayered heterostructure. This structure results in an ultrastable permeability of 13 up to 1 GHz, a relatively large saturation magnetization of 105 Am²/kg, and a low coercivity of 48 A/m. The ultimate compressive strength of the composite is also increased to 337.1 MPa due to the epitaxially grown interfaces between particles. The study deepens the understanding of magnetic vortices and provides an alternative concept for designing integrated magnetic devices, particularly for high-frequency applications such as inductors and transformers in more-than-Moore era integrated circuits.