Obama and Sarah Brown arrived at Maggie's Cancer Caring Centre at Charing Cross Hospital.
The facility features cutting-edge resources -- information, advice, and emotional counsel -- for victims of all types of cancer.
Following a private session with a cancer patient's family, Obama met with three male cancer patients regarding the center's benefits. She also shared cosmetic tips with female patients and said her own make-up artist participates in similar programs.
"This is pretty incredible," Obama said. "It's an oasis that's necessary for people who are struggling."
Obama enthusiastically participated in the center's birthday celebration by having tea. She presented an undisclosed gift to the center's chief executive, Laura Lee.