The news came despite Anthony Joshua, the IBF, WBO and WBA 'super' heavyweight champion, saying he wanted face-to-face talks with Wilder to ensure a fight is agreed this year, Sky Sports reported.
However, Wilder appears to have other plans, tweeting on Wednesday morning, "To all my fans, I want to announce that Luis Ortiz and I have signed for a rematch, with the date and site to be announced shortly. All my controversial fights must get dealt with ASAP."
Wilder beat Ortiz in their first fight in New York last year, knocking out the Cuban in the 10th round to inflict his only professional defeat.
The American's most recent fight was a first-round destruction of Dominic Breazeale to record the ninth-straight defense of his WBC title.
Joshua fights Andy Ruiz Jr. on Saturday and his promoter Eddie Hearn had urged him to concentrate on impressing on his US debut before calling out Wilder.
He said, "Do we have to make the Wilder fight? More than anything. Biggest fight in world boxing and one of the biggest heavyweight fights of all time.
"I'm scared of Ruiz Jr. and especially of Wilder – he can punch! But don't you want those moments, a chance to be undisputed?
"You think we don't want it? We want it so badly. AJ needs to say: 'Now! November or December, no excuses, let's do it'."