Vice President Kamala Harris' stepdaughter, Ella Emhoff, is firing back at J.D. Vance for his controversial “childless cat lady” remark aimed at women like her stepmom.

Ella -- the daughter of Kamala's hubby Douglas Emhoff -- was trailed by her Secret Service detail Thursday while walking her dog in Brooklyn, and a photog asked her about the crack from Donald Trump's running mate.

Ella wasn't exactly anxious to speak -- she took a pass on a question about the support for her stepmom -- but wasn't about to let Vance's comments go unchecked -- calling it "upsetting" that he'd say something like that.

She's not alone.

Even Jennifer Aniston weighed in ... saying she couldn’t believe Vance would say such stuff about women ... praying on IG his 2-year-old daughter, Mirabel, wouldn’t have to deal with IVF if she wants kids someday.

For background ... Vance uttered the highly offensive statement on Tucker Carlson's show back in 2021 -- saying Pete Buttigieg and women like Kamala are "childless cat ladies who are miserable at their own lives" and have "no direct stake" in America.

The clip resurfaced on social media this week in the wake of Trump picking him to be his VP.

Harris' supporters -- celebs and otherwise -- and now her stepdaughter are sounding off about Vance ... and you can bet his comment will come up again during a future debate and/or on the campaign trail.