We present a 3D shear‐wave velocity model of the southern African upper mantle developed using 30–200 s period Rayleigh waves recorded on regional seismic networks spanning the subcontinent. The model shows high velocities (∼4.7–4.8 km/s) at depths of 50–250 km beneath the Archean nucleus and several surrounding Paleoproterozoic and Mesoproterozoic terranes, placing the margin of the greater Kalahari Craton along the southern boundary of the Damara Belt and the eastern boundaries of the Gariep and Namaqua‐Natal belts. At depths ≥250 km, there is little difference in velocities beneath the craton and off‐craton regions, suggesting that the cratonic lithosphere extends to depths of about 200–250 km. Upper mantle velocities beneath uplifted areas of southern Africa are higher than the global average and significantly higher than beneath eastern Africa, indicating there that is little thermal modification of the upper mantle present today beneath the Southern African Plateau. Plain Language Summary: We present a 3D shear‐wave velocity model of the southern African upper mantle developed by modeling phase velocities of surface waves recorded on regional seismic networks spanning the African subcontinent. The model shows high velocities to depths of 250 km beneath the core of the Southern African Shield. At depths ≥250 km, the model shows little difference in velocities under most of southern Africa suggesting that the thickest lithosphere does not extend deeper than that. The model also shows that upper mantle velocities beneath the uplifted areas are not anomalous, indicating that there is little thermal alteration of the upper mantle present today beneath the Southern African Plateau. Key Points: Surface wave phase delays were inverted to create a 3D shear‐wave velocity model of the upper mantle beneath southern AfricaKalahari Craton lithosphere is defined by high velocities (∼4.7–4.8 km/s) beneath the Archean cratons and surrounding Proterozoic terranesUpper mantle velocity structure shows little evidence for present‐day thermal anomalies supporting the Southern African Plateau [ABSTRACT FROM AUTHOR]