On Sunday, the 32-year-old rapper — whose real name is Shad Moss – shared a paparazzi photo of Williams, 55, rocking a black bikini while on the beach.
He reportedly captioned the now-deleted picture: “They say its a hot girl summer,” along with several emojis which appeared to indicate he was mocking the talk show host's appearance, according to People magazine.
The post immediately drew the ire of Williams' fans with many of them coming to her defense.
“When u failed as a rapper so you gotta turn to making fun of older (more successful) women on the TL,” one Twitter user wrote.
Tweeted singer Ari Lennox: "You’re disgusting."
While others reminded the rapper that he has an 8-year-old daughter.
“You are raising a daughter….the way you speak about women… just sad…" commented another person.
E! News reports Bow Wow's post comes on the heels of Williams' show last week where she called out the artist for making a "very distasteful" comment about his ex-girlfriend Ciara during a nightclub appearance.
At the time, Bow Wow was reportedly captured in a video saying: “I had this b—h first" about the "Level Up" songstress.
"Bow Wow, I am mad at you … What're you doing," Williams said on Wednesday. "Bow Wow, I'm not hating on you, but young man, so what?
"It's very distasteful," Williams added. "We've all had somebody before we had you, man. We've all lived, but to be shirtless in a club and calling her a ‘b—h,' you were so wrong for that."
Reps for Bow Wow and Williams did not immediately respond to Fox News' request for comment.
Fox News’ Julius Young contributed to this report