According to Us Weekly, social media user commented: "She really need [sic] to cut his hair."
Not one to bow down to anyone, Kourtney quickly responded "She really need [sic] to not worry about kids that aren’t her own. He’s a happy boy."
Recently, the 40-year-old was also criticised after sharing photos from her family’s Finland vacation.
"Don’t your kids go to school? Their education is so important more than these trips," a follower commented.
"It was spring break, but travelling can be educational too," the Poosh Founder replied.
This isn’t the first time Kourtney has dealt with this argument from critics.
Earlier this year, the mother-of-three was also moved to defend her frequent vacations to another Instagram troll.
An Instagram troll wrote in August that her trips are the reason why "ppl say [she doesn’t] work."
"We all have our priorities," she wrote at the time, according to Us Weekly.
"So I’ll be making memories with my kids and amazing people while living my life to the absolute fullest."
"As women, we should be supporting each other for what allows us to be our best, not being so critical and judgmental of each other. We all do things our own way," the reality tv star added.