Tavares spent last season with Lazio, where he impressed by coach Marco Baroni.
The Portugal International has now signed downright with the Romans and written a contract to 2029.
Lazio announced: “SS Lazio announces that it has definitively registered the player Nuno Albertino Varela Tavares from Arsenal FC
“The player signed an employment contract until 30 June 2029.”
Tavares was in the books of Arsenal since 2021.