The Magpies winger, who joined Newcastle in September following his departure from AFC Bournemouth, has scored two goals in his last two appearances for his country after netting in the World Cup qualifiers against Israel and Faroe Islands.
However, the 27-year-old - who currently has 16 international caps to his name - has not featured for Steve Bruce's side since returning from international duty in March due to a groin injury.
The Tartan Army qualified for their first major men's tournament since 1998 back in November following a tense play-off victory against Serbia in Belgrade via a penalty shoot-out.
Steve Clarke's side begin their Euro 2020 campaign on Monday, 14th June at Hampden Park against Czech Republic and, following a highly-anticipated clash against England at Wembley Stadium, will return to home soil for their final Group D clash against 2018 World Cup finalists Croatia.
Norwich City defender Grant Hanley, who spent a year on Tyneside during the Magpies' Championship-winning season in 2016/17, is also included in the squad.
Scotland will face two friendlies against Netherlands and Luxembourg, playing on Wednesday, 2nd June and Sunday, 6th June respectively, before kicking off their European Championship campaign in Glasgow.
Scotland squad for Euro 2020:
Goalkeepers: Craig Gordon (Heart of Midlothian), David Marshall (Derby County), Jon McLaughlin (Rangers)
Defenders: Liam Cooper (Leeds United), Declan Gallagher (Motherwell), Grant Hanley (Norwich City), Jack Hendry (KV Oostende - on loan from Celtic), Scott McKenna (Nottingham Forrest), Stephen O'Donnell (Motherwell), Nathan Patterson (Rangers), Andy Robertson (Liverpool), Greg Taylor (Celtic), Kieran Tierney (Arsenal)
Midfielders: Stuart Armstrong (Southampton), Ryan Christie (Celtic), John Fleck (Sheffield United), Billy Gilmour (Chelsea), John McGinn (Aston Villa), Callum McGregor (Celtic), Scott McTominay (Manchester United), David Turnbull (Celtic)
Forwards: Ché Adams (Southampton), Lyndon Dykes (QPR), James Forrest (Celtic), Ryan Fraser (Newcastle United), Kevin Nisbet (Hibernian)
