The 41-year-old will remain at Albion until next summer before taking up his new role at St George's Park.
Dan was given permission from Albion to enter into talks with the FA after he expressed an interest in exploring other opportunities. The FA had officially approached him ten days prior to the talks.
Ashworth has been Sporting & Technical Director at Albion since July 2008.
"The Sporting & Technical Director post is a position we firmly believed was vital to the success of this football club and Dan has helped to shape this role. He has certainly taken on a challenging role within The FA and will leave with our best wishes."
Jeremy Pearce, West Bromwich Albion Chairman
Dan is now the second Albion official to be recruited by The FA following Roy Hodgson’s appointment as England Manager in May.