The 24-year-old was a surprise inclusion in the initial 26-strong party named on Monday, just days after the Magpies' exit from the Barclays Premier League was confirmed.
He now faces the task of forcing his way into Roy Hodgson's final 23, something he admits would be the biggest achievement of his career to date.
Townsend told www.nufc.co.uk: "It would be a dream come true. It's every young boy's dream to grow up and go on to play at a major tournament for their country, and I am no different.
"It would be the best achievement of my career so far - but there is still a long way to go and a lot of hard work. Hopefully in a couple of weeks, I will make the final 23.
"Playing for England and pulling on that shirt is a huge honour. You are deemed to be one of the 23 best English players, and to represent your country in any sport is the highlight of your career.
"Hopefully I can add to my 10 caps over this summer."
Townsend last played for his country as a substitute in a 3-0 qualifier victory in Lithuania in October, but had slipped from the reckoning as his time at former club Tottenham drew to a close.
But Newcastle's £12million summer swoop for him and his performances under new boss Rafael Benitez have helped to rekindle his international hopes.
Townsend said: "It's no secret that I hadn't been getting too much game time over the past season-and-a-bit, and Newcastle took a chance on me, brought me to the club and I can't thank them enough.
"Ever since the manager came in, you can see that he's taken my game to another level. I'm hugely grateful and if I get the opportunity to go to the Euros, I will be proud to do so representing Newcastle.
"From my performances over the last couple of months - and the team's performances - I knew I could do a good job for England, if selected.
"But you can't take anything for granted and you don't know what the national manager is thinking. All you can do is keep playing well on the pitch and hope that your good form is being noticed.
"I'm delighted that the manager noticed and recalled me to the squad. I was a bit surprised because I haven't been involved in the last few squads, but I was extremely delighted and it's a huge honour to be called up.
"The hard work starts now. I've got two weeks to try and force my way into the final 23."