Arsenal midfielder Xhaka will captain the team at his third World Cup and is among a host of Premier League players named in the squad, including Manchester City's Manuel Akanji (27) and Newcastle United defender Fabian Schar (30).
Winger Xhaqiri, now at Chicago Fire in Major League Soccer, will be heading to his fourth World Cup at the age of 31 with 108 caps to his name.
Yakin will take four goalkeepers to Qatar with injury concerns over first-choice goalkeeper Yann Sommer (33) and back-up Jonas Omlin (28), calling up Salzburg's Philipp Kohn (24) as one of two uncapped players in the squad.
Sommer, who has 76 caps, injured his ankle in Borussia Monchengladbach's match against Darmstadt last month while Montpellier goalkeeper Omlin sprained his ankle against Olympique Lyonnais on October 22.
Young Boys midfielder Fabian Rieder (20) is the other uncapped player and has been called up for the first time.
The squad also includes Nottingham Forest midfielder Remo Freuler (30) and Chelsea loanee Denis Zakaria (25), although Fulham defender Kevin Mbabu (27) is a notable absentee.
"We were spoiled for choice in some positions," Yakin said in a statement.
"Many players have delivered convincing performances in recent weeks and months. But in the end I had to limit myself to 26 names.
"I'm convinced that these 26 players can always help us to achieve our goals."
Switzerland open their World Cup campaign in Qatar against Cameroon on November 24 and also face Brazil and Serbia in Group G.
Switzerland Squad
Goalkeepers
Gregor Kobel (Borussia Dortmund)
Yann Sommer (Borussia Monchengladbach)
Jonas Omlin (Montpellier)
Philipp Kohn (RB Salzburg)
Defenders
Manuel Akanji (Manchester City)
Eray Comert (Valencia)
Nico Elvedi (Borussia Monchengladbach)
Fabian Schar (Newcastle United)
Silvan Widmer (Mainz)
Ricardo Rodriguez (Torino)
Edimilson Fernandes (Mainz)
Midfielders
Michel Aebischer (Bologna)
Xherdan Shaqiri (Chicago Fire)
Renato Steffen (Lugano)
Granit Xhaka (Arsenal)
Denis Zakaria (Chelsea)
Fabian Frei (Basel)
Remo Freuler (Nottingham Forest)
Noah Okafor (RB Salzburg)
Fabian Rieder (Young Boys)
Ardon Jashari (Luzern)
Forwards
Breel Embolo (Monaco)
Ruben Vargas (Augsburg)
Djibril Sow (Eintracht Frankfurt)
Haris Seferovic (Galatasaray)
Christian Fassnacht (Young Boys)
Follow Switzerland's opening game of the World Cup with Flashscore.
