Liverpool midfielder Alex Oxlade-Chamberlain also returns for the first time since March 2018 following a long-term knee injury, but there is no place for John Stones, Fabian Delph, Dele Alli or Eric Dier due to fitness concerns.
"We learned some lessons from last September on the importance of physical fitness at this time of year so that's dictated some of the squad," said Southgate.
"But also some exciting players we wanted to look at and involve and we look forward to seeing them on the grass next week."
Mings has impressed on Aston Villa's return to the Premier League, while attacking midfielders Mount and Maddison have started the season brightly with Chelsea and Leicester respectively.
Wan-Bissaka joined Manchester United in a £50 million ($61 million) move from Crystal Palace in June, but faces stiff competition at right-back.
Liverpool's Trent Alexander-Arnold and Kieran Trippier of Atletico Madrid are included as Kyle Walker, who started at in that position during the Nations League finals, has been left out.
However, Southgate stressed Walker's omission was not due to his form with Manchester City, but a desire to look at a host of young players with the Three Lions already in a strong position to qualify for next summer's Euros.
"We only have eight matches before I've got to name the squad for the European Championships," added Southgate.
"We have competition for places and we have got a depth of talent now because we have approached it slightly differently to look at younger players.
"We can't stand still and there are young players coming through for the long term for England and we need to start integrating them."
England thrashed the Czech Republic and Montenegro to start their qualifying campaign in March and will be confident of two more victories on home soil when Bulgaria visit Wembley on September 7 before Kosovo travel to Southampton three days later.
Squad in full:
Goalkeepers: Nick Pope (Burnley), Tom Heaton (Aston Villa), Jordan Pickford (Everton)
Defenders: Trent Alexander-Arnold, Joe Gomez (both Liverpool), Ben Chilwell (Leicester City), Michael Keane (Everton), Harry Maguire, Aaron Wan-Bissaka (both Manchester United), Danny Rose (Tottenham), Tyrone Mings (Aston Villa), Kieran Trippier (Atletico Madrid/ESP)
Midfielders: Ross Barkley, Mason Mount (both Chelsea), Jordan Henderson, Alex Oxlade-Chamberlain (both Liverpool), Declan Rice (West Ham), Harry Winks (Tottenham), James Maddison (Leicester)
Forwards: Harry Kane (Tottenham), Marcus Rashford, Jesse Lingard (both Manchester United), Jadon Sancho (Borussia Dortmund/GER), Raheem Sterling (Manchester City), Callum Wilson (Bournemouth)