In 1965 Premier Zhou En Lai gave a speech on the island of Zanzibar as part of his famous tour of Africa. When he had finished speaking his opening in lines in Chinese, his interpreter Ms. Shen Zhiying translated his words into fluent Kiswahili. Once she had spoken, the crowd erupted in wild cheers and ululations in response to hearing the words of their Chinese guest pronounced in their own language. In this paper I will argue that Ms. Shen Zhiying played a critical role in China-Africa diplomacy through her voice as a Kiswahili interpreter. I go further to explore the diplomatic and linguistic trajectories of two women translators and interpreters, Aysha Zaher and Shen Zhiying, who were engaged in Kiswahili language diplomacy in the 1960s and 1970s in China. Aysha Zaher was a Swahili teacher and translator from Zanzibar who spent ten years translating the works of Chairman Mao. Shen Zhiying was a Swahili teacher and translator from China who worked at the Foreign Languages University and also spent extended periods of time working in East Africa as an interpreter for political leaders, medical doctors and agricultural teams. The life stories of these two women shed light on the gendered nature of internationalist diplomacy and solidarity; the significance of translation and interpretation in China-Africa relations; and the role played by Kiswahili in global engagements of the Cold War era.