Giles will take charge of the side for the first time in the upcoming tours of India and New Zealand in January and February.
London: Ashley Giles will take over as England limited overs head coach, the England and Wales Cricket Board (ECB) announced on Tuesday as officials try to ease the burden on team director Andy Flower.
Story first published on: Wednesday, 28 November 2012 17:31
However, the ECB stressed Flower, the former Zimbabwe batsman, will remain team director and "continue to be responsible for the preparation and playing strategies for the England men's cricket teams supported by Ashley Giles".
There have been concerns the workload being carried by Flower for the past five-and-a-half-years, which has seen England win home and away Ashes series, could lead to him suffering from 'burn-out'.
Flower will continue to tour with the England Test side during both home and away series but will no longer be responsible for the day to day leadership of the England ODI and T20 sides, with Giles now taking on that responsibility.
In their statement the ECB said the new set-up would "provide a more efficient and sustainable use of coaching resources".
Giles, a former England left-arm spinner who was an Ashes winner as a player in 2005, is already a member of the England selection panel and as a coach helped guide Warwickshire, the club he represented during his first-class career, to the 2012 County Championship title.
But as a result of his new role, Giles will now give up his position with the Midlands county.
Both Flower, 44, and Giles, 39, will remain England selectors in a panel currently chaired by former Test off-spinner Geoff Miller.
Flower, who has taken short breaks from recent limited overs series, said in an ECB statement: "I'm very excited by these changes and very much looking forward to working with Ashley Giles as we look to build on the success England cricket has had in the last few years.
"The change in role will also allow me to thoroughly plan and prepare for each of our international series whilst spending the right amount of time at home with my young family."
Meanwhile Giles said: "I am delighted to have been appointed England ODI and T20 Head Coach and to be given an opportunity to coach at international level.
"I have worked closely with Andy in recent years as a selector and am looking forward to continuing to work together and to build on the progress that has been made with the ODI and T20 sides in recent years."
Giles will take on his new role immediately, with his first ODI series in charge in India before England play T20 and ODI matches in New Zealand.
In a separate statement, Warwickshire chief executive Colin Povey said the county champions were sad to see Giles leave but wished him well.
"This is a fantastic opportunity for Ashley and he leaves with our full support," said Povey.
"We are, of course, sad to see him leave so soon after helping us secure the LV County Championship, but he leaves behind a strong team ethos and the players are already working hard to prepare for next season."
England have won just one major ICC limited overs tournament -- the 2010 World Twenty20 -- but will look to take their first global 50-over title when they stage next year's Champions Trophy.