Pietersen, who had announced his retirement from the shorter formats in June and later made himself available for all cricket, has of late been in controversy over his text messages to South African players.
He was even left out of the squad for the third and final Test against South Africa which concluded on Monday at Lord's.
England selectors on Tuesday named a 15-player England squad and a 14-player England Women's squad.
Stuart Broad will lead a side looking to retain the ICC World T20 which they had won in the Caribbean in 2010 by defeating Australia in the final.
Eight members of the squad were involved in the 2010 victory and all members of the squad have previously represented England in the twenty over format.
National selector, Geoff Miller, said: "We are very much looking forward to beginning the defence of our World T20 title next month. We know that it will take exceptional cricket to retain the trophy and that begins with the first match against Afghanistan. This is a very balanced squad combining experienced players with some young talent who have done well at both international and domestic level this season and who are all very excited by the challenges ahead in Sri Lanka."
England squad: Stuart Broad (captain), Jonny Bairstow, Ravi Bopara, Tim Bresnan, Danny Briggs, Jos Buttler, Jade Dernbach, Steven Finn, Alex Hales, Craig Kieswetter, Michael Lumb, Eoin Morgan, Samit Patel, Graeme Swann, Luke Wright.
England women squad: Charlotte Edwards (captain), Tammy Beaumont, Arran Brindle, Katherine Brunt, Holly Colvin, Lydia Greenway, Jenny Gunn, Heather Knight, Danielle Hazell, Laura Marsh, Susie Rowe, Anya Shrubsole, Sarah Taylor, Danielle Wyatt.