A leadframe-based semiconductor package and a fabrication method thereof are provided. The leadframe-based semiconductor package includes a chip implanted with a plurality of first and second conductive bumps thereon, and a leadframe having a plurality of leads. The first conductive bumps are bonded to the leads to electrically connect the chip to the leadframe. The chip, the first and second conductive bumps, and the leadframe are encapsulated by an encapsulant, with bottom ends of the second conductive bumps and bottom surfaces of the leads being exposed from the encapsulant. This allows the second conductive bumps to provide additional input/output electrical connections for the chip besides the leads.