The 51-year-old revealed on her Instagram that she is auctioning off a nude portrait of herself taken by photographer Mark Seliger in November 1995.
The black-and-white image features the "Friends" star crossing her legs in front of her chest and resting her hands on her knees.
"My dear friend @markseliger teamed up with @radvocacy and @christiesinc to auction 25 of his portraits - including mine ☺️- for COVID-19 relief," Aniston captioned the post.
"100% of sales proceeds of this portrait will go to @NAFClinics, an organization which provides free coronavirus testing and care nationwide to the medically underserved," she added.
Besides Aniston, 25 other celebrity portraits of Seliger’s will also be auctioned off, including images of Leonardo DiCaprio and Oprah Winfrey. Proceeds from each sale will go the charity of the star's choosing.
“The first time I met Jennifer Aniston I knew she was going to be a big star. It was uncanny — you thought you knew her, or at least wished you knew her,” Seliger told Christie's about the actress.
“I was given an assignment to photograph the cast of 'Friends' and they were still a little stunned at how quickly the show had taken off. There was a wonderful stylist, a massive ball of energy, named Chris McMillan who was responsible for the famous 'Rachel' cut," he explained.
“Immediately after the shoot I recommended Jennifer for the cover of Rolling Stone magazine, which of course she got. Since then we’ve worked together many times — she’s incredibly loyal and still as lovely as the first time I met her.”