MicroRNAs (miRNAs) has been identified as diagnostic and prognostic biomarkers and predictors of drug response for many diseases, including a broad range of cancers, heart disease, and neurological diseases. The noninvasive theranostics system for miRNAs is very important for diagnosis and therapy of the cellular disease. Herein, a target-cell-specific theranostics nanoprobe for target-cell-specific delivery, cancer cells and intracellular miRNA-21 imaging, and cancer cell growth inhibition was proposed. The nanoprobe (FS-AS/MB) was prepared by simultaneously coupling of the AS1411 aptamer and miRNA-21 molecular beacon (miR-21-MB) onto the surface of Ru(bpy)₃²⁺-encapsulated silica (FS) nanoparticles. The FS nanoparticles synthesized by a facile reverse microemulsion method showed nearly monodisperse spherical shape with a smooth surface, good colloidal stability, a fluorescence quantum yield of ~21%, and low cytotoxicity. The antibiofouling polymer PEG grafted onto a silica shell reduced nonspecific uptake of cells. The ability of FS-AS/MB for target-specific cells delivery, simultaneous cancer cells, intracellular miRNA-21 imaging, and inhibition of miRNA-21 function and suppression of cell growth in vitro, were also demonstrated. The results of the present study suggested that the proposed nanoprobes would be a promising theranostics for different cancers by imaging and inhibiting other intracellular genes.