Hearn, who first entered the American market last year, told The Daily Telegraph: "When we came to the US, we really needed a platform that would give us the volume of dates we needed to grow, and we needed a huge warchest to go out and get the very best fighters in the US.
"My job is to put the biggest fights on DAZN in the US, and build the biggest stable of fighters ever seen in the US. With the warchest I've got, I have every opportunity to do it. There is no excuse.
"All the promoters in the US want us to fail. Everyone will say it's a new platform and it might not work. And I could see the argument, but not with the amount of money I have to spend."
Hearn hopes that the deal will provide exposure in the US to young British fighters, and said he will reveal at the end of June which fighters he has recruited to a 30-strong stable.
He added that there is "every chance" Joshua, who is a free agent in the US following the end of his Showtime deal, could fight on DAZN in the future. "Of course DAZN will be aggressively trying to recruit him to the channel," Hearn said.
The deal has been announced earlier than DAZN were originally hoping in order to allow the promoter to begin his recruitment of fighters.
Simon Denyer, the CEO of Perform Group, said the move is the latest step towards streaming services becoming the major players in sports broadcasting.
"We genuinely believe this is how all sport will be watched in three or four years," he said. "If you look at what has happened with music and what has happened in TV, with Spotify and Netflix, it has radically changed things very, very quickly."
DAZN, which launched in 2016, will challenge traditional pay-per-view fights in the US, the price of which Denyer believes has become "completely ridiculous".
DAZN is available in Canada, Germany, Japan, Austria and Switzerland. It shows Premier League and Champions League football in Austria and Germany, but Denyer said a move into the UK market is not currently a priority.
"We would love to launch in the UK, and we definitely will at some point," he said. "But we are handpicking markets based on the size of the market, the speed of broadband, the availability of rights and the price of rights. The UK does not come to the top of the list when you look at those."