Magnetic nanoparticle-supported lipid bilayers (SLBs) constructed around core-shell Fe3O4-SiO2 nanoparticles (SNPs) were prepared and evaluated as potential drug carriers. We describe how an oxime ether lipid can be mixed with SNPs to produce lipid-particle assemblies with highly positive ζ potential. To demonstrate the potential of the resultant cationic SLBs, the particles were loaded with either the anticancer drug doxorubicin or an amphiphilic analogue, prepared to facilitate integration into the supported lipid bilayer, and then examined in studies against MCF-7 breast cancer cells. The assemblies were rapidly internalized and exhibited higher toxicity than treatments with doxorubicin alone. The magnetic SLBs were also shown to increase the efficacy of unmodified doxorubicin.