The Seahawks were forced to hold off a late charge from the 49ers, with Smith making a vital interception in the endzone with just 22 seconds left to seal a 23-17 victory for his side.
After the match, Smith hailed a whole lifetime of work to get to the biggest stage in the NFL, where they will now face the Denver Broncos on February 2.
"To see all our work that we put in - the mornings, the nights, the weights, all your life, as a young player and in the NFL. It's amazing," Smith told The AP.
Super Bowl XLVIII will pit the number one seeds from the AFC and NFC together after both the Broncos and the Seahawks finished the regular season with 13-3 records.