Rory Patterson scored a hat-trick for the Candystripes in tonight's second-leg to complete a 5-0 win away from home to follow their 4-0 first-leg victory at the Brandywell.
Michael Duffy got the scoring underway in the 11th minute while Ramelton's Barry McNamee made it back to back European goals three minutes later.
Patterson's heroics started on the the hour, with the second in the 84th minute and a penalty four minutes from time gave the Strabane man the match ball.
Derry will play FC Shakhtyor Soligorsk of Belarus in the 2nd round.
Sligo Rovers are also into the next round.
After being held to a frustrating scoreless draw in Lithuania last time out, Sligo beat 10-man FK Banga by 4 goals to nil tonight at the Showgrounds.