The Sweden international has penned a five-year contract with the Gunners, and he will now link up with his new teammates in Asia for their pre-season tour.
The club confirmed that Gyokeres will wear the famous number 14 shirt, immortalised by Thierry Henry.
The London giants will reportedly pay the Portuguese club a guaranteed €63.5 million, plus €10 million in add-ons.
In Arsenal's official statement, manager Mikel Arteta said: “We’re absolutely delighted to welcome Viktor Gyokeres to the club.
"The consistency he has shown in his performances and availability have been outstanding, and his goal contributions speak for themselves."
In his first interview with his new employers, Gyokeres stated: “To be a part of this club and to score in this kit and with this badge in front of all the supporters, I can't wait. It will be an amazing feeling."
The man behind the mask: All you need to know about Viktor Gyokeres
Both Arsenal and Sporting had been locked in lengthy negotiations, with the transfer held up due to disagreements over the bonuses in the deal.
Sporting were reportedly keen on the add-ons to be based on performance, while Arsenal wanted to set more challenging targets.
There was also friction on Gyokeres' end after failing to report back for pre-season training in order to force a move to North London.
Arsenal set their sights on the 27-year-old after initially targeting RB Leipzig striker Benjamin Sesko, but saw no progress beyond interest.
Gyokeres gives Gunners extra edge as they look to gain Premier League glory
Gyokeres joined Sporting from Coventry in July 2023 and scored an impressive 97 goals in 102 appearances, helping the club win back-to-back Primeira Liga titles.
Interest in his services increased following the most recent campaign, which saw him net 54 times in 52 games.
Gyokeres has played 26 games for Sweden since making his debut in 2019, scoring 15 goals.
Arsenal face Newcastle in the Singapore National Stadium on Sunday ahead of the concluding game of their tour, against Tottenham in Hong Kong on July 31st. Their first match of the new Premier League season is away at Manchester United on August 17th.