Tottenham winger Townsend and Everton midfielder Barkley have been in fine form during the opening stages of the Barclays Premier League and Hodgson has responded by handing them their first international call-ups.
England resume their World Cup qualification campaign a week on Friday against Moldova at Wembley before they play Ukraine in Kiev four days later.
Barkley, 19, scored on the opening day of the season for Everton, while 22-year-old Townsend has performed brilliantly for Spurs since he returned from a loan spell at QPR.
Raheem Sterling has been promoted from the Under-21 squad even though he has only played 18 minutes for Liverpool so far this season.
Striker Rickie Lambert retains his place in the squad after scoring on debut against Scotland earlier this month, while uncapped Celtic stopper Fraser Forster has been called up to replace the injured West Brom keeper Ben Foster.
Daniel Sturridge returns to the squad after sitting out the game against the Scots, while fellow striker Jermain Defoe retains his place in a 27-man squad despite not starting a game for Spurs this season.
New Under-21 manager Gareth Southgate has named Wilfried Zaha and Luke Shaw among his 25-man squad for the Euro 2015 qualifiers against Moldova on September 5 and Finland four days later.