The 22-year-old became one of the mainstays in Sergio Conceicao's setup last season and racked up a total of six goals and 14 assists in 27 Primeira Liga matches.
Only Benfica's Rafa (15) set up more goals in the Portuguese top flight than Vieira, who won his second Primeira Liga title with Porto in 2021-22, as well as the Taca de Portugal.
Liverpool were understood to have first refusal on Vieira's signing this summer, while Manchester United were also recently linked with a move for the versatile midfielder.
However, Arsenal quickly emerged as the frontrunners for his signature, and Porto have now announced that Vieira will be heading to North London in a statement released to the Securities Market Commission.
The Gunners will pay an upfront fee of €35m (£29.9m) to sign the Portugal Under-21 international, with a potential €5m (£4.3m) included in add-ons.
"Football Clube do Porto – Futebol, SAD, under the terms of article 248º nº1 of the Securities Code, hereby informs the market that it has reached an agreement with Arsenal FC for the definitive transfer of the registration rights of professional football player Fabio Vieira for the amount of €40M (forty million euros), of which €5M (five million euros) are dependent on the achievement of sporting goals," the statement read.
"It is further informed that the final agreement is still being finalized and is expected to be implemented in the coming days."
Vieira is understood to have arrived in London on Thursday night and will soon complete his medical at Arsenal before signing terms on a five-year contract.
The midfielder is supposedly set to pocket €130,000 (£111,000) per week in North London, and Arsenal were able to negotiate a fee with Porto rather than paying the entirety of his €50m (£42.7m) release clause.
A recent report claimed that the Gunners could have been ready to announce Vieira's arrival on Friday, but confirmation is now expected to come over the weekend or at some point next week.
Vieira leaves Porto having registered a total of 10 goals and 18 assists in 76 senior appearances for the club, and he has scored 13 goals in 21 appearances for Portugal's Under-21 side, although he is still waiting for his first senior cap.
The 22-year-old - who is comfortable as a number 10, number eight or out wide - will become the Gunners' second signing of the summer transfer window after Marquinhos joined from Sao Paulo.
Despite bolstering their midfield with Vieira's signing, Mikel Arteta's side are still pursuing Leicester City's Youri Tielemans, but the Foxes are reportedly still waiting for an official offer from the Gunners. body check tags ::