The Argentina international is moving to the Spanish club in a deal worth up to 34.2 million pounds, with Tottenham set to receive 29.9 million pounds up front and a further 4.3 million pounds in potential add-ons. Spurs will also retain a 15 per cent sell-on clause.
Romero, 28, joined Tottenham from Atalanta in 2021, initially on loan, and went on to make 156 appearances for the club. He was appointed captain in 2025 and played a key role in the side that ended Tottenham's 17-year wait for a major trophy by beating Manchester United 1-0 in the Europa League final.
In a farewell message to supporters, Romero reflected on his time at Spurs and admitted his spell at the club had not always been flawless.
"I know I wasn't perfect," he said. "But one thing gives me peace: I always gave everything. I defended this shirt with pride and with all my heart."
Romero said winning a trophy had been his ambition when he arrived and that achieving it allowed him to leave believing he had made his mark on the club.
"When I arrived, I had a clear dream: to leave my name in this club's history," he added. "I knew the only way was through hard work, sacrifice and achieving something that had seemed so difficult for so long: lifting a trophy again. And we did it."
The centre-back also thanked Tottenham's players, coaches, staff and supporters, describing the club as a home for both himself and his family.
"I leave with a heart full of memories and enormous pride for everything we lived and achieved together," Romero wrote.
Romero leaves Tottenham as a World Cup winner and two-time Copa America champion, having established himself as an important member of Argentina's defence. He featured seven times for his country at this summer's World Cup after also helping them win the 2022 World Cup and Copa America titles in 2021 and 2024.
His move to Atletico will bring an end to a five-year Tottenham chapter in which he became a defensive leader and captain while helping deliver the club's long-awaited European trophy.
"I'm leaving the club, but a part of my heart will always remain here," Romero said. "Once I was one of you. Today, I leave as one of you forever."
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