Thiago Silva has signed a one-year extension to remain at Chelsea until the end of the 2023-24 season.
The Blues targeted youth in the January transfer window, splashing out huge sums of cash on Enzo Fernandez, Mykhaylo Mudryk and Benoit Badiashile as part of a spending spree.
Of the seven permanent first-team additions to arrive at Stamford Bridge last month, only Mudryk is aged over 21. Joao Felix, at 23, is the oldest player to have come in during Chelsea's splurge, though he signed on a loan deal from Atletico Madrid.
Experience, then, will be crucial for Graham Potter, and Chelsea on Friday confirmed they had finalised an agreement with 38-year-old Silva.
The former Milan and Paris Saint-Germain defender had been set to become a free agent at the end of the campaign, but will now stay on for another year.
"I am honestly so happy to continue my career with the Blues," Silva told Chelsea's official website.
"When I signed my first contract here, it was to just do one year. Now it is already the fourth!
"I could not have imagined that, but really it is a very special moment for me to sign and stay at Chelsea."
Chelsea chairman Todd Boehly and co-controlling owner Behdad Eghbali added: "We're delighted that Thiago has decided to continue with Chelsea.
"He's a world-class talent, as he's proven over many years for club and country, and his experience, quality and leadership skills are vital to our vision going forward.
"We're thrilled he has extended his contract with us, and we look forward to more success with him ahead."
Silva, who has played 74 Premier League games since joining Chelsea in 2020, has won the Champions League, Super Cup and Club World Cup during his time in west London.
The Blues are enduring a disappointing campaign and need a turnaround in fortunes if they are to secure European football.
Potter's team have won just two of their last 12 league games and sit ninth, 10 points adrift of the Champions League places, ahead of a trip to West Ham on Saturday.