Brown released the news of the cancellation before confirming it to FOX Sports on Tuesday.
"Fight against @NateDiaz209 isn't happening. I'll update you guys soon as I get the word on opponent/date/ thanks for the support as always!" the Ohio resident tweeted.
"He didn't sign the contract," Brown then told FOX Sports via text message.
The 34-year-old Brown admitted that he wasn’t privy to the exact details regarding the cancelation, only that his manager told him that the fight wasn’t going to happen at UFC 189.
Diaz seemed unhappy with the fight from the off and never actually confirmed that he accepted the bout.
He stated in various interviews that he had no problem with facing Brown, but he was unhappy with the way in which the proposed meeting came about.