Surface enhanced Raman scattering (SERS) is widely used in all kinds of detections due to its ultrahigh sensitivity and selectivity. Micromotors when using as SERS sensors, or the so-called “hotspots on the fly”, can combine both controlled mobilities and SERS sensing capacities, and are ideal for versatile in-situ detections. In this work, we have successfully fabricated mobile SERS sensors by growing gold nanospikes onto magnetic microsphere surfaces. These mobile micromotors can act as normal SERS sensors, which is characterized by the trace detection of thiram, a highly toxic fungicide. The detection limit can reach 0.1 nM, as good as most other Nobel metal deposited substrates. With magnificent magnetic gradient forces, separation of pathogenic bacteria from bulk solution has been achieved once these magnetic micromotors bind with bacterial cells. Manipulated propulsion of micromotors, on the other hand, enables them to approach and contact pathogenic bacterial cells on command and further acquire Raman spectra under controlled degree of contact, a capability never seen with passive sensors. Our robotic SERS sensors have demonstrated unique sensing characterization with controlled manipulations along with detections.