Nevertheless, Walker's elevation is a shock and comes at the end of a period when the 20-year-old has excelled in loan spells with both QPR and Villa.
Walker, on loan at Villa having been deemed surplus to requirements at parent club Tottenham, is joined in the squad by club team-mates Stewart Downing, Ashley Young, Gabriel Agbonlahor and Darren Bent.
The former Sheffield United defender has appeared for England at Under-19 and Under-21 level, making his debut for the former before he had ever appeared in a league match for the Blades.
He subsequently joined Tottenham at the start of last season, although he struggled to make an impact at White Hart Lane and it was not until he signed a loan deal with QPR in September that he started to catch the eye.
Capello's lack of options at right-back are emphasised by the fact Johnson is still favoured to start in that role against the Danes, even though he has spent the last few weeks at left-back for Liverpool after an inconsistent campaign.
England squad to face Denmark:
Defenders: Leighton Baines (Everton), Gary Cahill (Bolton), Ashley Cole (Chelsea), Michael Dawson (Tottenham), Glen Johnson (Liverpool), Joleon Lescott (Man City), John Terry (Chelsea), Kyle Walker (Aston Villa)
Midfielders: Gareth Barry (Man City), Stewart Downing (Aston Villa), Steven Gerrard (Liverpool), Frank Lampard (Chelsea), James Milner (Man City), Scott Parker (West Ham), Theo Walcott (Arsenal), Jack Wilshere (Arsenal), Ashley Young (Aston Villa)