Two of Argentina's goals came in the first half as Lionel Messi scored from the penalty spot in the 34th minute, followed just five minutes later by another goal this time from the boot of Julian Alvarez.
The Manchester City forward lit up the Lusail Stadium again in the second half, with a solo run, and sealed the deal in the 69th minute after some great work from Messi down the wing.
Croatia were looking for their second successive final but it was not to be for the European side. Argentina will now face either reigning champions France, or upstarts Morocco in the final, euronews.com reported.
Tuesday's semi-final saw Messi tie the record for most appearances at the World Cup when he played for the 25th time for Argentina at football's biggest tournament.
MA/PR