A facile approach to the stereoselective synthesis of spiroimidazolidinones was described. A variety of novel polycyclic spiroimidazolidinones derived from isatin were prepared by employing easily available 2-pyridyl prolinamide as a chiral scaffold. Interestingly, the N-2-pyridyl motif played a vital role in improving the diastereoselectivity of this protocol. As a result, excellent diastereoselectivities (>20:1 dr) and good to excellent yields (60–96%) were achieved under extremely mild reaction conditions.