The trio were due to be out of contract on June 30 and had to agree extensions before midnight on Tuesday, June 23 in order to stay beyond that date.
The Athletic reports that the Gunners have now come to terms with the defensive trio, including turning loan deals for Pablo Mari and Cedric Soares into permanent stays.
Mari and Cedric, the latter of whom is yet to make his debut for the club having been sidelined by injury since joining on loan from Southampton in January, have reportedly signed four-year contracts at the Emirates Stadium.
David Luiz, meanwhile, is understood to have agreed a one-year stay in North London to ensure that his error-strewn cameo against Manchester City in the first game back after lockdown will not be his final appearance for the club.
Luiz was on the pitch for just 25 minutes after coming off the bench, but in that time committed an error leading directly to a goal, conceded a penalty and was sent off.
Mikel Arteta's side, who have lost both matches back since lockdown, are next in action away to Southampton on Thursday.