The Chelsea youngster who is on loan at Crystal Palace has been called up to the England senior team for the first time.
The midfielder was representing England Under-21s earlier this week and played 89 minutes in a 3-1 win against Czech Republic.
He has played for England at all levels from Under-17 to Under-21 – earning 36 caps – and will join Gareth Southgate’s squad before Monday night’s clash with San Marino. The Three Lions recently defeated Albania 5-0 in their first of two World Cup qualifiers this international break.
Speaking with cpfc.co.uk, Gallagher said: “I’m really happy and excited to be called up to the senior squad. I’m determined to make the most of the experience and know I have a lot of hard work to do.
“I’d like to thank everyone that has helped me in my career so far and I’ll do my best to make them proud.”
So far, the on-loan midfielder has been named Palace’s Player of the Month twice, scored four goals and collected two assists.