By SABC Sport
23rd January 2023
The 22-year-old featured for Poland at the World Cup in Qatar and was in the stands at the Emirates Stadium on Sunday evening to watch his new side beat Manchester United.
Kiwior, who had a spell in Belgium with Anderlecht earlier in his career, moved to Serie A from MSK Zilina in August 2021, and made 43 appearances during his time with Spezia.
Arsenal said Kiwior, a left-sided central defender, had signed a long-term contract, with the fee reported to be in the region of £21million.
Gunners boss Mikel Arteta told the club's website: "It's great that Jakub is joining us. He's a young versatile defender who has shown huge potential and qualities with Spezia in Serie A and also at international level with Poland.
"Jakub is a player who will give us strength and quality to our defensive unit. We welcome Jakub and his family to Arsenal and look forward to working with him."
Arsenal sporting director Edu added: "We're delighted to have completed the signing of Jakub Kiwior. He's a young talent who we've been monitoring for a while now."