A semiconductor package includes: a package substrate; an interposer disposed on the package substrate; a first semiconductor chip mounted on the interposer; a second semiconductor chip mounted on the interposer adjacent to the first semiconductor chip, the second semiconductor chip having an overhang portion that does not overlap the interposer in a vertical direction; a first underfill disposed between the package substrate and the interposer, the first underfill having a first extension portion extending from a side surface of the interposer; a second underfill disposed between the interposer and the second semiconductor chip, the second underfill having a second extension portion extending to an upper surface of the package substrate along at least a portion of the first extension portion of the first underfill, wherein the second extension portion protrudes from the overhang portion contact the upper surface of the package substrate.