Luiz has joined the reigning Serie A champions on a 16-month contract after leaving Arsenal at the end of the 2020/2021 season.
Italian sides Salernitana and Lazio were reportedly eyeing moves for the former Brazil international but Luiz has taken the option to return to his homeland.
"He's been all over Europe, and was looking for a new home!”, the official Flamengo Twitter account wrote.
"He's won all over the world, and now is in a place where our anthem says "win, win, win...". We want to welcome David Luiz to Mengao! Our Nation is more than ready to see you in the Sacred Mantle!"
Luiz spent 14 years in Europe after leaving Vitoria in 2007 and represented the likes of Benfica, Chelsea, Paris Saint Germain and Arsenal.
His most successful spell came across two spells at Stamford Bridge, where he made 248 appearances and won the UEFA Champions League, two Europa League trophies, one Premier League and two FA Cups.
The 34-year-old also won one Portuguese League title at Benfica while his time in France produced two Ligue 1 titles, two Coupe de France and one Coupe de la Ligue.
Luiz, who won 57 caps for Brazil, added another FA Cup to his laurels during his time with Arsenal.
