Manchester United striker Welbeck and Liverpool defender Johnson missed last Saturday’s 1-0 friendly victory over Norway in Oslo because of lingering fitness issues.
But the duo were both named to travel to Poland and Ukraine in a squad showing only two changes from the original 23 unveiled by manager Roy Hodgson earlier this month.
Everton defender Phil Jagielka comes in for the injured Gareth Barry, ruled out on Monday, while Birmingham goalkeeper Jack Butland replaces John Ruddy, who broke a finger in training last week.
England also confirmed squad numbers for the tournament on Tuesday, and in a possible indicator of Hodgson’s preferences in attack, handed Liverpool striker Andy Carroll the No.9 shirt.
Carroll is expected to start for England in their opening matches against France and Sweden in the absence of the suspended Wayne Rooney.
England squad for Euro 2012
Goalkeepers: Joe Hart (Man City), Rob Green (West Ham), Jack Butland (Birmingham)
Defenders: Glen Johnson (Liverpool), Phil Jones (Man United), John Terry (Chelsea), Joleon Lescott (Man City), Gary Cahill (Chelsea), Ashley Cole (Chelsea), Leighton Baines (Everton), Phil Jagielka (Everton)
Midfielders: Theo Walcott (Arsenal), Stewart Downing (Liverpool), Alex Oxlade-Chamberlain (Arsenal), Steven Gerrard (Liverpool), Frank Lampard (Chelsea), Scott Parker (Tottenham), Ashley Young (Man United), James Milner (Man City)
Forwards: Wayne Rooney (Man United), Danny Welbeck (Man United), Andy Carroll (Liverpool), Jermain Defoe (Tottenham)