The musicians were joined by their wives as they embraced for a snap posted to 76-year-old Stewart's Instagram.
In the first photograph, Stewart hugged Wood, 73, while his wife Penny Lancaster did the same to the Rolling Stones star's wife Sally Humphreys.
They all lined-up for the second photo before swapping hug partners again, this time with Wood and Humphreys, 43, facing the camera.
"Back together again #oldfaces #hugs," Stewart wrote before tagging Mayfair's The Arts Club, a private members' club.
Lancaster, 50, posted the same pictures to her own page, writing: "Couldn’t be happier to see our dear fiends @ronniewood and @sallywood1 to celebrate the first official day out/IN with a big hug.
"The first time in a very long time. #hugs #friends @the_arts_club."
Wood recently shared that he had been given the all-clear in lockdown after a second cancer diagnosis.
In an interview released in April, he divulged that he'd had small-cell cancer.
Watch: Rod Stewart gifted Penny Lancaster a narrowboat for her 50th birthday
Referencing the concept of a “higher power” as by Alcoholics Anonymous and Narcotics Anonymous, he told The Sun: "All I can do is stay positive in my attitude, be strong and fight it, and the rest is up to my higher power.
“I’m going through a lot of problems now, but throughout my recovery, you have to let it go. And when you hand the outcome over to your higher power, that is a magic thing.”
He had previously battled lung cancer in 2017.
The four-year-old twin daughters he shares with Humphreys, Gracie Jane and Alice Rose, had been born in the previous year.