Studies have shown the potential of nanomaterials for the accurate and early detection of cancer. The aim of the present study was to design and evaluate the value of prostate-specific membrane antigen (PSA)-targeted manganese oxide–mesoporous silica nanoparticles (Mn–Msns) for the detection of prostate cancer. Mn–Msns were prepared, and then conjugated with the PSA antibody and Cy7 to create the multimodality PSA-Mn-Msn-Cy7. Their particle size, zeta potential, stability and magnetic resonance imaging (MRI) features of the nanoparticles were characterized. Optical and MR imaging were evaluated in cell and tumor-bearing mouse models. The Mn in tissues was measured by inductively coupled plasma mass spectrometry. The fabricated nanoparticles were stable and showed good T₁relaxivity. The targeted nanoparticles accumulated to a great extent in prostate cancer cells in vitro but not in noncancerous cells. In vivo studies further demonstrated a targeted distribution of PSA-Mn-Msn-Cy7 to cancer tissues as shown by high optical and T1 signals. The targeted distribution was also confirmed by determining the Mn content in the cancer tissues. Our data demonstrate that PSA targeted fluorescence and MR dual-functional nanoparticle can visualize prostate cancer and can be used as NIRF/MR contrast agents.