Sant Joan Despí has four neighborhoods: Barri Centre (population: 16.169), Les Planes (10.841), Pla del Vent – Torreblanca (3.668) and Sant Joan (2.752).
Barri Centre's borders are Creu de Muntaner street in the north, Cornellà in the south (Maria Rosa street and the tramway's garage), the Barcelona – Vilafranca railway in the east and Maria Tarrida street in the west.
Les Planes' borders are Barcelona Avenue and Àngel Guimerà street in the north; les Flors avenue, Àngel Guimerà street and Cireres street in the south, meeting Cornellà; Baix Llobregat avenue in the east and Gran Capità street in the west.
Pla del Vent – Torreblanca meets the Torreblanca park and the national road 340 in the north, the B23 motorway in the south, Sant Just and B23 in the east and the Barcelona – Vilafranca railway in the west.
Sant Joan's borders are the B23 motorway in the north, Sant Martí de l'Erm street in the south, Fructuós Gelabert in the west and Baix Llobregat avenue in the east.