Keith Downing's Young Lions travel to Borrolha for an intriguing fixture at the Estadio Municipal de Agueda on Thursday, 14th November before facing Iceland at Wycombe Wanderers' Adams Park on Tuesday, 19th November, with Longstaff one of two new faces in the party, alongside West Ham goalkeeper Joseph Anang.
Longstaff's selection continues a remarkable few weeks for the North Shields-born 19-year-old, who scored the winner on his Premier League debut against Manchester United last month, winning the Match of the Day Goal of the Month award in the process and earning a nomination for the Premier League's own goal of the month award.
And, moments after being given the good news, Longstaff told nufc.co.uk: "It's great to be called up - obviously I haven't had the privilege yet of going away with them, so I'm looking forward to it.
"Every World Cup, you watch England and you sit in the bars that are full of the fans, but this will be my first time away with them so hopefully it's good.
"When you play in the Premier League, you're on show to everyone and thankfully for me, that's helped me get into the England set up. I was in the physio room when you came and told me I was in the squad, and I'm looking forward to it."
Longstaff will be joined in the squad by one of his closest friends - Everton defender Lewis Gibson, who came through Newcastle's Academy before moving to Goodison Park in July 2017.
"When he went to Everton, you still text but you don't see him as often, so we'll get to go back to our under-18 days, when we used to play together, which should be enjoyable," he smiled.
"It's a bit daunting going into a new squad - I imagine the lads will all be sound and they'll be good lads, but when you get that one person you can relate to and stick with, he'll hopefully help me a bit which should only be beneficial for me.
"We go to Portugal then come back to England, so there should be a bit of time there to get to know the lads.
"But that's not until next week - we've still got a massive game on Saturday where hopefully we can come away with three points and give us a big momentum boost going into the international break, and for when we come back.
"I think four points from the last two games is pretty decent and if we can go and get another win, which I think we're capable of, it would continue a good run."
The England under-20s squad for the games against Portugal and Iceland is: Joseph Anang (West Ham United), Joe Bursik (Accrington Stanley, loan from Stoke City), Billy Crellin (Fleetwood Town), Jayden Bogle (Derby County), Nathan Ferguson (West Bromwich Albion), Lewis Gibson (Everton), Tariq Lamptey (Chelsea), Joel Latibeaudiere (FC Twente, loan from Manchester City), Japhet Tanganga (Tottenham Hotspur), Brandon Williams (Manchester United), Flynn Downes (Ipswich Town), Andre Dozzell (Ipswich Town), Angel Gomes (Manchester United), Matthew Longstaff (Newcastle United), Emile Smith-Rowe (Arsenal), Marcus Tavernier (Middlesbrough), Luke Bolton (Luton Town, loan from Manchester City), Tyrese Campbell (Stoke City), Jack Clarke (Leeds United, loan from Tottenham Hotspur), Danny Loader (Reading), Ian Poveda Ocampo (Manchester City).
