Metal matrix syntactic foams represent a highly relevant subject in the research field of closed-cell metal-ceramic composite foams. The composite nature of the material with ceramic hollow spheres embedded within a metal matrix, represents a porous material with superior strength in comparison to conventional metal foams, making them suitable for the use in a wide range of structural applications. The Al-based metal matrix syntactic foams are most commonly investigated, as they provide a high potential due to the combination of brittle ceramic hollow spheres with a ductile and low-density Al matrix. The possibility to change the interface between different ceramics and Al by adding Mg to the matrix, enables an easy way to influence the foam’s key aspects of porosity, microstructure and mechanical properties, starting at the production. Since past studies have solely investigated simple combinations of Al-based matrices and ceramic hollow spheres, there still is a huge research potential in studying the impact of different Mg contents in AlMg alloys of syntactic foams. For this reason, syntactic foams, made of AlMg alloys with different Mg contents (min. 5 wt%) and two different kinds of oxide ceramic hollow spheres (Al2O3 and SiO2), are produced using a low-pressure infiltration casting technique. The modification of the Mg fraction positively influences the wetting behavior of the different ceramic spheres, resulting in a change of the metal-ceramic interface’s chemical composition and microstructure, which are investigated using light and scanning electron microscopy (EDX). The as-gained results from the microstructural characterization are compared with the results of the compressive testing in order to gain a holistic understanding of the influence of the Mg content on the interface and microstructure of AlMg- Al2O3/ SiO2 syntactic foams and their respective mechanical properties.