UFC officials have confirmed to ESPN that Anderson (8-2) has withdrawn from her scheduled 145-pound title fight against Justino (17-1) due to personal reasons.
Ranked bantamweight Tonya Evinger (19-5) will replace Anderson in the fight, which serves as UFC 214's co-main event. Evinger, 36, is the current 135-pound champion of all-female fight promotion Invicta FC.
"Due to personal issues, Megan Anderson has been forced to withdraw from her UFC 214 bout against Cris 'Cyborg' Justino on July 29," a UFC official stated.
Representatives for Anderson, 27, told ESPN she is "looking forward to fighting Cyborg for a UFC title at a later date," but they declined further comment on her current status.
Anderson said in a statement posted to social media that "this is the biggest struggle I have faced yet, but like I always do, I will come back stronger and better than before. ... I'm coming for whoever has that belt."
The UFC introduced its female featherweight division earlier this year -- and it has been a rough start.
De Randamie's first title defense was supposed to be against Justino, who is widely considered the most dominant female fighter of all time. The newly crowned champ refused to accept that matchup. The UFC was ultimately forced to strip de Randamie of the title earlier this month.
That opened the door for the UFC to sign Anderson, who has fought for Invicta since 2015 and also holds a title there. The Anderson-Justino matchup was announced just eight days ago.
It's a huge development for Evinger, who was scheduled to move up in weight and headline an Invicta event on July 15 in Kansas City. The Missouri native has been fighting professionally since 2006. She has recorded a finish in all but four of her 19 career wins.