In this work two different sizes of Fe3O4 nanoparticles (NPs) have successfully been synthesized by changing reaction parameter. Prepared Fe3O4 NPs have been characterized for its structural, morphological, and magnetic properties by using XRD, FESEM, TEM, SAED and VSM techniques. XRD and SAED patterns confirmed the formation of cubic phase Fe3O4 NPs. Crystallite sizes estimated using the Debye–Scherrer equation of both prepared Fe3O4 NPs using less (S1) and more (S2) NaBH4 were found to be ~9 and ~18 nm respectively. Both TEMand FESEM results suggested nearly spherical and random morphology of both S1 and S2 prepared Fe3O4 NPs with average particles sizes of 22 and 27 nm respectively. VSM result revealed superparamagnetic nature of the prepared Fe3O4 NPs. In the last section of this work, prepared Fe3O4 NPs have successfully been coated with albumen to form biocompatible multifunctional Fe3O4@Alb nanoparticle. These Fe3O4@Alb NPs may find potential applications in targeted drug delivery due to its magnetic tunability, biocompatibility and inexpensiveness.