A flexible colloidal seeded-growth strategy was developed to synthesize all-oxide semiconductor/magnetic hybrid nanocrystals (HNCs) in various topol. arrangements, for which the dimensions of the constituent material domains can be controlled independently over a wide range. The authors' approach relies on driving preferential heterogeneous nucleation and growth of spinel cubic Fe oxide (IO) domains onto brookite TiO2 nanorods (b-TiO2) with tailored geometric parameters, by time-programmed delivery of organometallic precursors into a suitable TiO2-loaded surfactant environment. The b-TiO2 seeds exhibit size-dependent accessibility towards IO under diffusion-controlled growth regime, which allows attainment of HNCs individually made of a single b-TiO2 section functionalized with either one or multiple nearly spherical IO domains. In spite of the dissimilarity of the resp. crystal-phases, the two materials share large interfacial junctions without significant lattice strain being induced across the heterostructures. The synthetic achievements were supported by a systematic morphol., compositional and structural characterization of the as-prepd. HNCs, offering a mechanistic insight into the specific role of the seeds in the control of heterostructure formation in liq. media. The impact of the formed b-TiO2/IO heterojunctions on the magnetic properties of IO also was assessed.