Jorginho joined Premier League leaders Arsenal from Chelsea on transfer deadline day on Tuesday for a reported fee of £12 million ($15 million).
"Welcome to The Arsenal, Jorginho," the club said in a post on their official Twitter account.
Gunners manager Mikel Arteta said the 31-year-old Italy international would bring "intelligence, deep leadership skills and a huge amount of Premier League and international experience".
The midfielder, who is understood to have signed an 18-month deal at the Emirates Stadium, told Arsenal.com: "I'm very excited for this new challenge and I just can't wait to be on the pitch to be honest.
"Everything has happened so fast. I was a bit surprised, but I took the opportunity of this amazing challenge.
"It's an important shirt. It's an amazing club, a big one, and I'm really excited and happy to be here."
The former Napoli player has made 143 Premier League appearances for Chelsea, with whom he won the Champions League in 2021.
He was also part of the Italy team that won the European Championship the same year.
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