The Gunners were largely outclassed by the Premier League champions on Sunday.
Raheem Sterling opened the scoring with a cool finish early in the first half before Bernardo Silva lashed in City's second after the interval, leaving Guardiola to sing the champions' praises.
Emery was hired to replace Wenger following the Frenchman's exit at the end of a dismal campaign which saw Arsenal labour to a sixth place finish in the Premier League.
Despite cup successes in recent years, Arsenal have slipped behind their rivals in the Premier League and have consistently failed to reach the latter stages of the Champions League.
Arsenal Supporters' Trust (AST) said it was a "dreadful" day for the club, adding that the club was too important to be owned by one person.
Mesut Ozil, named as captain, was quickly into his stride with midfield partner Henrikh Mkhitaryan against a PSG line-up shorn of its World Cup stars.
Unai Emery has been busy in the transfer market in his first weeks in charge.
Ozil, who was born in Germany to Turkish-origin parents and lifted the World Cup in 2014, felt he was unfairly singled out for their shock group-stage exit at this year's tournament.
Atletico goalkeeper Antonio Adan starred as he saved three goals before coolly slotting the winner himself.
Mesut Ozil dropped a bombshell by announcing his retirement from Germany duty and accused the president of the German FA, Reinhard Grindel, of racism.
Mesut Ozil had faced a barrage of criticism for having his photograph taken with Turkey's authoritarian President Tayyip Erdogan in May.
In addition to Mesut Ozil, Mohamed Elneny and Alex Iwobi would play a full part in the Singapore tour with Arsenal travelling on July 22.
The England international made his Gunners debut in 2008 and has made 197 first-team appearances.
The Gunners, who finished sixth last season, had previously signed Swiss defender Stephan Lichtsteiner on a free from Juventus, while midfielder Granit Xhaka extended his contract.
City amassed 100 points and scored 106 goals while finishing 19 points clear of second-placed Manchester United in the 2017/18 season.
The 34-year-old was out of contract at the Serie A champions and joins the Gunners on a free transfer.
Emery, 46, left PSG this month after winning Ligue 1 and four domestic cups in two seasons in the French capital.
Wenger guided Arsenal to three Premier League titles, including the famous Invincibles 2003-04 unbeaten season, and seven FA Cups.