Peter Moores was named England coach for the second time as the cricket board continued its overhaul following the humiliating 5-0 Ashes rout in Australia at the start of the year.
The 51-year-old succeeds Zimbabwean Andy Flower who stepped down after five years in charge following the whitewash Down Under in January.
Moores coached England for two years from 2007 before he was sacked after a fall-out with leading batsman Kevin Pietersen whose international career was ended by the England and Wales Cricket Board (ECB) after this year's Ashes defeat.
Moores, a journeyman player and a former coach of Sussex, took charge at Lancashire after leaving England and in 2011 led them to the outright County Championship title for the first time in 77 years.
Former international spinner Giles was favourite to get the England job but the team's poor World Twenty20 campaign in Bangladesh last month, in which they failed to get past the group stage, looks to have counted against him.
Moores faces a major rebuilding job following the end of Pietersen's international career, the retirement of experienced off-spinner Graeme Swann and the ongoing problems faced by batsman Jonathan Trott.
The right-hander, England's established number three in recent years, left the Ashes tour after the first Test due to a stress-related illness and announced on Friday he was taking a further break from the game.
England play home test series against Sri Lanka and India this year with the one-day World Cup in Australia and New Zealand looming in 2015.