"Are you kidding??? I can't consider this post hilarious so I'll just unfollow!" one enraged fan wrote.
"Terrible. not the slightest bit funny," one follower commented, while another added: "Hmmmmm don't think this is funny … sorry I may be a bit sensitive."
Another person added that while Watts' post was clearly staged "it does scream white upper-class privilege".
"She can afford to attempt humour publicly in this way, in a way that someone with lesser societal status could not," they argued.
Watts soon responded in the comments to the controversy explaining that she "didn't mean to offend".
"My humour is sometimes irreverent. Photo was staged obviously," she added.
But others on Watts' Instagram post defended the star, labelling the negative reaction "embarrassing".
"Great Post. Happy Mother's Day! For those offended by this, you sadly have no sense of humour," one person wrote.
Watts shares her two sons with former partner Liev Schreiber, who she split from in 2016 after 11 years together.
The Australian actress, who lives in New York, was most recently linked to actor Billy Crudup, who she met while filming Netflix show Gypsy.
Last November it was confirmed Watts would be starring in the highly-anticipated Game of Thrones prequel, The Long Night.
According to Variety Watts will play a "charismatic socialite hiding a dark secret".
