The former Benfica man has spent the last three years in North London since being scouted by sporting director Edu, and he initially made an impression as Kieran Tierney's understudy.
Tavares memorably lit up the Emirates with an explosive display against Aston Villa in October 2021, on what was his first Premier League start, which preceded a brief run in the first XI.
However, the 24-year-old's Arsenal downfall began when he was substituted in the first half of an FA Cup loss to Nottingham Forest just a couple of months later, which triggered an angry reaction from Tavares at the City Ground.
The Portugal youth international still managed to force his way back into the team at the end of the 2021-22 season due to Tierney's latest injury, scoring his first goal for the club in a 3-1 home win over Manchester United.
Tavares move confirmed after training pictures
Tavares ended his debut season at the Emirates with one goal and two assists from 28 matches across all competitions, but he has not made a competitive appearance for the club since May 2022.
The defender managed to reignite his career during a temporary spell with Marseille in the 2022-23 season, netting six times in 39 matches, although he was allegedly also guilty of disciplinary indiscretions during his time in France.
With Oleksandr Zinchenko, Takehiro Tomiyasu, Jurrien Timber and Jakub Kiwior all at Mikel Arteta's disposal, Tavares was unable to get back into the Spaniard's good books last summer and joined Nottingham Forest on a temporary deal, although he only played 12 games due to injury.
Despite affirming that he wanted to do his utmost to impress the manager in pre-season, Tavares was always expected to head elsewhere, and Lazio curiously uploaded images of him in training a few hours before his transfer was confirmed.
The Gunners did not mention a possible permanent move in their statement, but Lazio confirmed that Tavares would stay at Stadio Olimpico if certain unspecified sporting conditions are met next season.
Arsenal 'agree sell-on clause' for Tavares
Arsenal will reportedly receive between £7m and £7.5m if Tavares joins Lazio on a permanent deal, and the Gunners will also retain a significant sell-on clause, said to be in excess of 25%.
Tavares becomes the second player in a matter of hours to leave Arsenal, who confirmed earlier on Monday that Belgian midfielder Albert Sambi Lokonga had joined Spanish outfit Sevilla on loan.
Lokonga's deal also includes an option for a permanent move, which will bank the Premier League powerhouses approximately £10.1m if it is triggered next summer.
Reiss Nelson, Emile Smith Rowe, Aaron Ramsdale, Eddie Nketiah, Thomas Partey and Tierney are also expected to leave the club in the coming weeks.