On the ribbon, the 38-year-old wrote a message "Simi kunye kulesisimo" -- which translates to "We stand together in this moment" -- in a local language called Xhosa.
"Uyinene's death has mobilized people across South Africa in the fight against gender based violence, and is seen as a critical point in the future of women's rights in South Africa," the Instagram post said.
"The Duchess has taken private visits and meetings over the last two days to deepen her understanding of the current situation and continue to advocate for the rights of women and girls."
Meanwhile husband Harry finished his tour of Angola and on Sunday will then begin a tour of Malawi sans Meghan and baby son, Archie Harrison.
The trio are expected to be reunited on Tuesday in Johannesburg.
WATCH: Meghan Markle kisses little girl's hand during crying meltdown