"The landmark agreement will see all 63 matches... live-streamed, free to view on DAZN worldwide," read a statement from FIFA.
A source close to the negotiations told AFP the contract was worth around one billion euros ($1.05 billion).
The announcement came on the eve of Thursday's tournament draw which is set to take place in Miami.
DAZN chief executive officer Shay Segev called the deal "groundbreaking".
"We're committed to ensuring that every fan can watch every moment of the thrilling action from this new prime club tournament," he said.
The agreement comes after multiple media reports suggested that DAZN could receive a major cash injection from Saudi Arabia's Public Investment Fund (PIF).
In October, PIF, which is involved in numerous sports investments including LIV Golf, Newcastle United and the ATP and WTA tennis tours, denied the reports.
PIF said at the time it was "not currently engaged in discussions with DAZN on this matter and has no current plans to invest in the company".
DAZN was announced the global distributor for the Saudi series of 'Riyadh Season' boxing fights and the broadcaster also has rights, in several markets, to the Saudi Pro League football competition.
FIFA are expected to announce next week that Saudi Arabia will host the 2034 World Cup. The Gulf nation is the only bidder for the tournament.
FIFA had initially held talks with Apple about broadcasting the tournament but those discussions reportedly ended in July and the organisation launched a tender process.
FIFA president Gianni Infantino hailed the deal as a great one for fans.
"Through this agreement, billions of football fans worldwide can now watch the most widely accessible club football tournament ever - for free," he said in a statement.
The tournament will see some of the world's best club teams battle it out in what is effectively a curtain-raiser for the 2026 World Cup taking place a year later in the United States, Canada and Mexico.
Twelve top clubs from Europe, including Manchester City, Real Madrid, Bayern Munich and Paris Saint Germain, will feature alongside top teams from South America, Asia, Africa and Oceania.
In November, Inter Miami, who feature eight-times Ballon d'Or winner Lionel Messi, were handed a place in the tournament to represent the host nation.
Games will take place across the United States from June 15 to July 13. The opening game will be held in Miami with the final at MetLife Stadium in New Jersey.
Yet for many, FIFA president Gianni Infantino's passion project is a tournament too far, an unwelcome addition to an already crowded global calendar that exhausted players say has pushed them close to breaking point.
Javier Tebas, the chief of Spain's La Liga, has been one of the Club World Cup's most outspoken critics, telling Infantino in October to cancel the tournament, citing apathy from broadcasters and opposition from clubs.
