Guehi played the full game on the left side of a back three with nearly 12,000 supporters present at the national stadium to see which team would join Norwich City and Watford in the Premier League next season.
Brentford, who beat Swansea’s in last season Championship play-off semi-finals in which Guehi also featured, started the better and went ahead in the 10th minute through Ivan Toney’s 33rd goal of the season. He converted from the penalty spot after Freddie Woodman in the Swans goal fouled Bryan Mbeumo.
The Bees doubled their advantage through Emiliano Marcondes on 20 minutes and there was no route back for Swansea, who created little and were reduced to 10 men for the final half-hour. Brentford saw the game out comfortably and will be the 50th different team to play in the Premier League, having last been in England’s top flight 74 years ago.