The Spain forward has signed a contract until 2031 for a reported fee of around €50m (£42.7m), arriving as a replacement for Gonçalo Ramos, who left for AC Milan in July.
Speaking at his pre-match press conference ahead of the Trophée des Champions against Lens, Luis Enrique — who gave Torres his senior Spain debut and now reunites with him in Paris — expressed his satisfaction with the signing.
"I'm happy about his arrival," he said. "I think we're improving the team, we're always looking for opportunities.
"He's an international player, we know him and he adapts perfectly because he can play anywhere.
"With his mentality, I think it's important to have this type of player. We continue working with the president and Campos on the transfer market and we're looking to improve the team."
Torres himself struck an ambitious tone in a statement released by the club.
"I'm delighted to be beginning a new adventure at such an ambitious club as Paris Saint-Germain," he said. "I'd like to thank president Nasser Al-Khelaïfi, Luis Campos and coach Luis Enrique for giving me the opportunity to join the team, which I hope to help win as many trophies as possible."
The 26-year-old scored the extra-time winner against Argentina to help Spain win their second World Cup last month, having already enjoyed a strong season with Barcelona, scoring 21 goals and adding three assists in 49 appearances as the Catalan club won La Liga. He trained with his new PSG teammates on Saturday morning but is not expected to be available for Sunday's match against Lens.
Torres becomes the second high-profile forward PSG have signed this summer, following the arrival of Maghnes Akliouche from Monaco, as the European and Ligue 1 champions continue to strengthen a squad that beat Aston Villa to win the UEFA Super Cup in midweek.
PSG could yet balance the books by allowing Bradley Barcola to leave, with Liverpool continuing to push for a deal, while Luis Enrique's press conference also touched on the futures of Barcola and fellow forward Ibrahim Mbaye.