The England Under-21s head coach has called upon 25 players for the matches, with four of those reporting just for the game against Wales on Monday 19 May.
As players born in 1992, Tom Ince, Carl Jenkinson, Jesse Lingard, Wilf Zaha and Danny Ings are too old for the Toulon fixtures, so will depart from the group after the match at the Liberty Stadium in Swansea.
Watch highlights of England's last game against Wales in March
From there, the remaining members of the squad will fly out to southern France, where they will face an initial four games against Qatar, Colombia, Brazil and Korea Republic.
Those matches will give Southgate an opportunity to consider his options for next season as well as provide a different experience for the players, with two qualifiers left to play in September following the Wales game. England have a six-point lead at the top of Group 1 with away trips to Lithuania and second-placed Moldova still to come.
His options for the games this month have been limited, with a number of players unavailable due to injury or involvement in The FA Cup Final and the Championship play-off final at Wembley on 24 May.
There is an international recall for Chelsea midfielder Josh McEachran, who has not featured for the Under-21s since last summer’s Euro Finals in Israel and spent this season on loan in the Championship with Watford and Wigan Athletic.
And Southgate has handed call-ups to a number of players who will be linking up with the Under-21s for the first time.
Brighton & Hove Albion striker Solly March receives his first call-up at any level and is joined in the squad by Amex Stadium team-mate Jake Forster-Caskey, who has previously featured for England at U16, U17 and U18 level.
Fulham striker Cauley Woodrow, who scored his first goal in the Premier League last weekend, is named among the forwards over three years since his last international appearances for England U17s in the Algarve Tournament of 2011 when he was playing with Luton Town.
There are also places for defenders Tyias Browning, Luke Garbutt, Ben Gibson and Brad Smith and midfielders Jordan Cousins and Jordan Obita, who have all featured for England in previous age groups in recent seasons.
The squad will meet up at St. George’s Park on Thursday to begin their preparations, before travelling to South Wales on Sunday for the Wales match.
From there, the squad for Toulon will head to France on Tuesday afternoon ahead of the opening game of the Tournament against Qatar on Thursday 22 May.
They will then take on Brazil on Monday 26 May, Korea on Wednesday 28 May and Colombia on Friday 30 May.
Goalkeepers: Jonathan Bond (Watford), Jack Butland (Stoke City), Sam Johnstone (Manchester United)^.
Defenders: Tyias Browning (Everton), Eric Dier (Sporting Lisbon), Luke Garbutt (Everton), Ben Gibson (Middlesbrough), Carl Jenkinson (Arsenal)*, Michael Keane (Manchester United), Liam Moore (Leicester City), Brad Smith (Liverpool).
Midfielders: Nat Chalobah (Chelsea), Jordan Cousins (Charlton Athletic), Jake Forster-Caskey (Brighton & Hove Albion), Josh McEachran (Chelsea), James Ward-Prowse (Southampton).
Wide: Tom Ince (Blackpool)*, Jesse Lingard (Manchester United)*, Jordan Obita (Reading), Nathan Redmond (Norwich City), Wilfried Zaha (Manchester United)*^
Forwards: Saido Berahino (West Bromwich Albion), Will Keane (Manchester United)**, Danny Ings (Burnley)*, Solly March (Brighton & Hove Albion), Cauley Woodrow (Fulham).
* Will only be available for Wales match.
^ Withdrawn from squad.
** Replaces Harry Kane (Tottenham Hotspur)