The breakthrough follows Guimaraes joining Newcastle's training camp in Spain on Monday, where he held discussions with club officials and incoming manager Mathias Jaissle and reiterated his desire to leave, a conversation that moved negotiations between the two clubs towards a final agreement.
Arsenal are expected to pay the £75m fee after having a first offer rejected on Monday before returning with an improved second bid, according to the Newcastle Chronicle. Guimaraes will now be expected to undergo a medical later this week before completing his move to north London, with personal terms said to have been agreed for some time.
Newcastle United are understood to be happy with the deal, which represents a significant profit on the £40m they paid Lyon for the midfielder in 2022, though his former club retain a 20% sell-on clause on any profit, meaning Newcastle are likely to bank closer to £60m of the headline fee.
Guimaraes becomes the third key player to leave St James' Park this summer, following Anthony Gordon's move to Barcelona and Sandro Tonali's switch to Tottenham, continuing a pattern that began with Alexander Isak's departure to Liverpool last summer. Arsenal identified Guimaraes as a target after deciding they needed a player capable of both playing alongside and covering for Declan Rice and Martin Zubimendi, who both showed signs of fatigue after playing more than 50 matches each last season.
BBC Sport report that Arsenal hope to complete the signing within the next 48 hours, with the Brazilian midfielder currently awaiting permission to leave Newcastle's training camp in La Manga to complete the formalities of his move to the Emirates Stadium.
The move would represent one of Arsenal's most significant pieces of business this summer, adding a proven, physically imposing midfielder capable of both partnering and covering for Rice and Zubimendi across a punishing fixture list that will again include Champions League and domestic cup commitments.
Guimaraes has established himself as one of the Premier League's most complete midfielders during his three and a half years at Newcastle, combining defensive intensity with genuine quality on the ball, and his arrival would give Mikel Arteta considerably more rotation options in the middle of the park than he had last season.
For Newcastle, the sale continues a summer of significant upheaval that has also seen Eddie Howe depart as manager, leaving Jaissle with the task of rebuilding a squad stripped of several of its most influential figures just as the new campaign begins.