Chelsea, which agreed a 10-year kit deal with adidas worth in the region of £300 million (A$593 million) in June 2013, said the size of the deal with tyre manufacturer Yokohama Rubber was commercially sensitive.
But it has been reported the five-year contract is worth £40 million (A$79 million) per season, second only in the Premier League to Manchester United's deal with United States car manufacturer Chevrolet, which is worth a reported £47m (A$93m) per season.
Yokohama Rubber replaces Korean electronic giant Samsung, which has sponsored Chelsea since 2005 in a deal which was re-signed in 2013 and worth a reported £18m (A$35m).
A Chelsea statement read: "Chelsea Football Club is delighted to unveil The Yokohama Rubber Company Ltd as our new official shirt partner in our largest-ever commercial deal.
"This places Chelsea right at the top of European football, with one of the biggest shirt sponsorships ever signed.
"This partnership with one of the world's leading tyre manufacturers is for an initial term of five years and begins at the start of the 2015/16 season.
"It will see the Yokohama brand appearing on all of our shirts from our first team to our youth teams."
The agreement was concluded on Thursday, four days before Chelsea plays Tottenham in the League Cup final.
Yokohama Rubber chairman Tadanobu Nagumo flew to London from Tokyo to appear in an official launch photoshoot with Chelsea chairman Bruce Buck, manager Jose Mourinho and captain John Terry.
Terry's contract expires at the end of the season and his presence suggests his standing remains strong at the Blues, which is likely to extend his deal for a further year.
Chelsea hopes the shirt deal will help the club, owned by Russian billionaire Roman Abramovich, in its bid to be self-sufficient.
Chelsea plans "to be one of Europe's leading football clubs with a self-financing model which is fully compliant with the UEFA Financial Fair Play rules", the statement added.
Former Liverpool chief executive Christian Purslow was influential in the deal after joining Chelsea as head of global commercial activities last October.
Buck said: "We believe that Yokohama will play a key role in helping us drive our global expansion in international markets such as the US, where they have operated with distinction for many years.
"Also, of course, Chelsea having such an esteemed and historic Japanese company as our partner enables us to accelerate our development in their home market too."
Nagumo added: "This shirt partnership with Chelsea will give Yokohama an opportunity to showcase our company to a huge worldwide audience thanks to Chelsea's ever-growing popularity.
"We look forward to launching our iconic new Chelsea Yokohama shirt this summer."
Chelsea will likely make Japan a key future destination on pre-season tours, although the arrangements for the 2015 summer tour are understood to already be in place and do not include a trip there.
Buck added: "I would also like to express my sincere gratitude to Samsung, with whom we have had a successful and rewarding relationship since 2005.
"Chelsea has demonstrated through that 10-year partnership that we can play a critical role in helping our partners achieve their global growth objectives. We look forward to accomplishing similar success with Yokohama."
