Without giving financial details, Chelsea said it represented the largest commercial deal in the Premier League club's history.
"Nike will produce strips for the first team, academy and ladies teams, as well as a full range of clothing for Chelsea’s millions of supporters around the world," the club said in a statement.
Chelsea's current kit is produced by Adidas, which said in May it had reached a mutual agreement to end its deal on June 30, 2017, instead of in 2023 as originally agreed, allowing the club to enter a new agreement with another competitor.
Media reports have indicated Adidas were paying Chelsea an estimated 30 million pounds ($43.38 million) a year, with the Nike deal likely to be double that figure.
Adidas agreed in 2014 to pay 750 million pounds ($1.1 billion) to replace Nike as sponsor of Manchester United for a decade.
"This is an incredibly exciting and important deal for the club," Chelsea director Marina Granovskaia told the club website (www.chelseafc.com).
"We believe Nike will be able to support our growth into new markets as well as helping us maintain our place among the world’s elite football clubs."
Chelsea, owned by Russian billionaire Roman Abramovich, won the Premier League title in 2014-15 but a poor run of form last season meant they failed to qualify for European football.
They are currently seventh in the standings after seven games.
(Reporting by Alan Baldwin, editing by Pritha Sarkar)
