Liverpool winger Sterling, Manchester United midfielder Powell and Tottenham forward Townsend have all been selected by Young Lions boss Stuart Pearce for the upcoming two-legged Euro 2013 play-off against Serbia.
"For Raheem, to have an insight into the senior team, is fantastic," Pearce told the Football Association's official website.
"He's been in our development squads and has done extremely well for Liverpool and credit to Brendan [Rodgers], who has given him his chance. We are pleased to have him.
"Andros Townsend has also done well and has been around Tottenham's first team squad consistently this year.
"I'm really looking forward to bringing them into the squad to give us a lift. They couldn't come in at a more crucial time."
England U21 squad for Serbia fixtures
Ryan Bennett (Norwich City) Steven Caulker (Tottenham Hotspur) Nathaniel Clyne (Southampton) Craig Dawson (West Bromwich Albion) Tom Lees (Leeds United) Jack Rodwell (Manchester City) Danny Rose (Sunderland - loan from Tottenham Hotspur) Adam Smith (Tottenham Hotspur) Andre Wisdom (Liverpool)
Jordan Henderson (Liverpool) Tom Ince (Blackpool) Henri Lansbury (Nottingham Forest) Jason Lowe (Blackburn Rovers) Josh McEachran (Middlesbrough - loan from Chelsea) Nick Powell (Manchester United) Jonjo Shelvey (Liverpool) Raheem Sterling (Liverpool) Wilfried Zaha (Crystal Palace)