Brentford survived a nervy finish and beat Swansea City 3-1 in the final match at Griffin Park to reach the Championship play-off final.
The Bees, who last played in the top flight in 1947, missed out on automatic promotion on the last day of the season and then lost the semi-final first leg 1-0 in Wales.
But a superb start on Wednesday set Brentford on their way to a 3-2 aggregate success.
Ollie Watkins raced onto Mathias Jensen's defence-splitting pass after 11 minutes and finished calmly as Swansea were punished on the counter-attack.