James' previous deal was due to expire in 2028, which made him one of the club's priorities for a renewal. He signed that contract shortly after the takeover by Todd Boehly and Clearlake Capital in 2022.
He has been a starter for 19 of his 26 Premier League appearances with the Blues this season and has made 225 appearances in total for the club.
"When you see Reece from afar, you admire him. He can play many different positions technically, he can score goals, defend, his athleticism," said Rosenior.
"The thing that impresses me most is his humility. You realise why he's having, and will have, the career he's had as captain of Chelsea. He will be our leader for as long as I'm here.
"It has been a really good two and a half months with him."
James won the Champions League in 2021 with Chelsea, along with the Uefa Super Cup in the same year and the 2025 Conference League and Club World Cup, and was named captain three years ago.
Talks are thought to have progressed quickly, with James encouraged by how his recovery from a series of injuries has developed after several disrupted seasons.
He underwent surgery in December 2023 in an attempt to fix a recurring hamstring injury.
On the pitch, he has been effective in full-back and midfield roles.
It is understood he has impressed with improvements in his leadership since early criticism under former head coach Enzo Maresca.
James has stated that earning a place in England's 2026 World Cup squad is a major goal, having missed the last two tournaments through injury.
He played in the qualification matches against Albania and Latvia in early 2025 after a two-year international absence.
He withdrew from the squad for October's friendlies against Wales and Latvia with injury, but he returned in November and played in the 2-0 win against Serbia at Wembley.
"I am over the moon to have extended my contract - Chelsea means so much to me," James told the club website., external
"I have always said I want my peak years to be here."
