The media mogul and lifestyle guru revealed the news on Instagram.
"This evening, I planned to host a garden party at The Plaza on behalf of my favorite skincare line, @mariobadescu. But I’m sad to report that I tested positive for Covid-19," Stewart wrote in the caption of a video showing part of the display set up at the planned garden party.
Stewart, 80, told fans, "I am feeling fine but I am sticking to the rules and isolating," which means she wasn't able to attend the function as planned.
"I’m heartbroken to be missing the celebration of over 50 years of amazing skincare and the launch of ‘The Martha Facial’ at their NYC flagship - which is a special offer of the facial I’ve been receiving there for more than forty years!" she added. "Cheers to what I’m sure will be a fabulous event."
Over 400 guests attended the event The Plaza in New York City, which was honoring the 50-plus years of skincare with Mario Badescu, and their long-standing relationship with Stewart. Joey Cabasso, President of Mario Badescu, read a heartfelt message from Stewart to guests in her absence, which was similar to what she posted on Instagram.
“I have been a customer of Mario Badescu since the 1960s when Mr. Badescu was still alive and creating his magical products. When Mario died the business was taken over by his 2nd in command Mr. Genesco and I continued to avail myself of all of the wonderful services – facials, massages, waxings, manicures and pedicures. I have always stocked my guest rooms, as well as my own bathrooms, with everything Mario," read Stewart's message. "The Cabasso family has elevated and expanded the Mario Badescu brand into new territory. One can now purchase products in department stores, beauty shops, mass market makeup retailers and even on QVC. I continue to visit the 52nd Street Spa where I have all of my special treatments. Thank you so much for years and years of wonderful service for me, my family and my friends."
While Stewart was not at the event, there were a few celebrity guests, including Real Housewives Leah McSweeney, Kelly Bensimon and Margaret Joseph, as well as Love Island’s Melinda Berry, Bachelor alum Peter Weber and Piper James and Disney star Sky Katz.
In January 2021, Stewart took to social media to share that she'd gotten vaccinated for the coronavirus, and encouraged others to do the same.
Also this week, actress and Jeopardy! host Mayim Bialik announced she has tested positive for COVID-19 as well and took to Instagram to share an update on her condition and warn followers that the virus is "no joke."