Borussia Monchengladbach attacking midfielder Reyna appeared as a substitute in the USA's friendly defeats to Belgium and Portugal in March after impressing Pochettino during last November's international window.
Reyna has played only a handful of games at club level since the turn of the year, making only eight appearances in the Bundesliga as a substitute for Monchengladbach.
However the 23-year-old remains one of the most technically gifted attacking players available to Pochettino as the Argentine coach prepares for the USA's World Cup Group D opener against Paraguay in Los Angeles on June 12.
The USA were drawn into Group D with Australia, Paraguay, and Turkey.
Reyna was at the center of an explosive controversy in Doha four years ago, when it emerged after the tournament he had almost been kicked out of the camp by then coach Berhalter over his attitude in training.
That in turn led to Reyna's mother informing US Soccer of a physical altercation in 1991 between Berhalter and his then girlfirend, and now wife, which triggered an investigation by US Soccer.
Pochettino's squad was announced at a roster reveal event in New York on Tuesday.
Little suspense surrounded the event, with details of Pochettino's selection leaking out in US media reports for several days leading up to Tuesday's formal announcement.
As expected, Europe-based players make up the bulk of Pochettino's squad with the likes of AC Milan's Christian Pulisic, Juventus's Weston McKennie and Monaco's Folarin Balogun all included alongside English Premier League players Tyler Adams (Bournemouth), Brenden Aaronson (Leeds), Chris Richards (Crystal Palace) and Antonee Robinson (Fulham).
Among the Major League Soccer players included in the roster are former coach Berhalter's son, Sebastian, the Vancouver Whitecaps midfielder.
Full squad
Goalkeepers: Chris Brady (Chicago Fire), Matt Freese (New York City FC), Matt Turner (New England Revolution)
Defenders: Max Arfsten (Columbus Crew), Sergino Dest (PSV), Alex Freeman (Villarreal), Mark McKenzie (Toulouse), Tim Ream (New England Revolution), Chris Richards (Crystal Palace), Antonee Robinson (Fulham), Miles Robinson (FC Cincinnati), Joe Scally (Borussia Monchengladbach), Auston Trusty (Celtic)
Midfielders: Tyler Adams (Bournemouth), Sebastian Berhalter (Vancouver Whitecaps), Weston McKennie (Juventus), Giovanni Reyna (Borussia Monchengladbach), Cristian Roldan (Seattle Sounders), Malik Tillman (Bayer Leverkusen)
Forwards: Folarin Balogun (Monaco), Ricardo Pepi (PSV), Christian Pulisic (Milan), Timothy Weah (Marseille), Haji Wright (Coventry City), Alejandro Zendejas (Club America)