The last tournament of the 29-year-old Wozniacki's professional career came in January at the Australian Open. The Dane won her Grand Slam title there in 2018.
She was supposed to face off against 23-time major champion Williams in Copenhagen, Denmark, on May 18 in a match dubbed "The Final One.''
Wozniacki wrote Tuesday on Twitter that their exhibition will be rescheduled because "the safety and health of everyone is most important.''
She added in another post that tickets already purchased "will still be good, once we pick a new date.''