Flanagan made his first England appearance from the bench in a 2-2 draw with Ecuador in Miami last night as the Three Lions prepare for the World Cup in Brazil, with their first match taking place in Menaus on June 14 against Italy.
Gerrard said: “Congratulations to Flanno and his family on his England debut tonight, I know how much it means to them all. Well done mate!”
The full-back has had a terrific season for Liverpool and has covered well for the Reds following the injury to Jose Enrique, and has also filled in for Glen Johnson when he has been on the sidelines.
It earned him a place on Roy Hodgson’s stand-by list for the World Cup.
Flanagan has made a total of 25 appearances for Liverpool this season, mostly at left-back, and has scored on one occasion – in a 5-0 away win against Tottenham Hotspur.
He is likely to play a big part for his club next season as they look to kick on from last season's surprise second place finish.