Leeds United midfielder Kalvin Phillips, as expected, is also in the party, while there has also been a call-up for former Whites loanee Ben White.
Patrick Bamford has not been named in the squad and there is also no place for Tottenham Hotspur defender Eric Dier, who was recently watched by England boss Gareth Southgate in Spurs's 3-1 loss at Elland Road.
Liverpool's Trent Alexander-Arnold has been named in the squad, alongside one-time York City defender Ben Godfrey, who is named in the senior party for the first time alongside Ramsdale and White.
The likes of Maguire, Phillips, Jordan Henderson and Nick Pope are all to be assessed over the coming days due to injury issues, with Southgate set to therefore wait until June 1 before naming his final 26 for the finals.
On uncapped duo White and Godfrey, Southgate said: "They are both exciting young defenders, there are others we have been looking at that we really like.
"These two are flexible, they play in different roles, this is a great opportunity to get to them a bit better for them to work with the team.
"There is no way of knowing how long they will be with us at this stage but it should be a fantastic experience for them."
Yorkshire-born Harry Maguire, John Stones, Kyle Walker, Dominic Calvert-Lewin, Mason Greenwood and Phillips are all in the squad.
England under-21 custodian Ramsdale was named as United’s player of the season before the club's final game of the Premier League season against Burnley at Bramall Lane on Sunday and has been rewarded for a consistent campaign which ended in excellent fashion.
It earned him a nomination for the EA Sports Player of the Month award for May, with Alisson, Gareth Bale, Christian Benteke, Sadio Mane, Nicolas Pepe, Rodrigo and Joe Willock also on the shortlist.
England squad: Goalkeepers: Dean Henderson (Manchester United), Sam Johnstone (West Brom), Jordan Pickford (Everton), Aaron Ramsdale (Sheffield United).
Defenders: Trent Alexander-Arnold (Liverpool), Ben Chilwell (Chelsea), Conor Coady (Wolves), Ben Godfrey (Everton), Reece James (Chelsea), Harry Maguire (Manchester United), Tyrone Mings (Aston Villa), Luke Shaw (Manchester United), John Stones (Manchester City, Kieran Trippier (Atletico Madrid), Kyle Walker (Manchester City), Ben White (Brighton)
Midfielders: Jude Bellingham (Borussia Dortmund), Jordan Henderson (Liverpool), Jesse Lingard (West Ham), Mason Mount (Chelsea), Kalvin Phillips (Leeds), Declan Rice (West Ham), James Ward-Prowse (Southampton)
Forwards: Dominic Calvert-Lewin (Everton), Phil Foden (Man City), Jack Grealish (Aston Villa), Mason Greenwood (Manchester United), Harry Kane (Tottenham), Marcus Rashford (Manchester United), Bukayo Saka (Arsenal), Jadon Sancho (Borussia Dortmund), Raheem Sterling (Man City), Ollie Watkins (Aston Villa)