It looks like the 87-year-old Justice has recovered from a couple recent hospitalizations and is feeling spry enough to serve as the marriage officiant for Barb Solish, Communications Director at the National Alliance on Mental Illness, and her hubby, Danny Kazin.

Solish shared a photo of RBG directing their Sunday nuptials and said ... "2020 has been rough, but yesterday was Supreme."

Solish also quashed any COVID-19 concerns for Ruth too, by pointing out she and her husband tested negative before the wedding.

As we reported ... the Justice was hospitalized in late July for a non-surgical procedure -- her second trip that month after also suffering from an infection. Add that to news of her cancer returning, creating a major cause for concern about her well-being.