BEIJING—New Chinese first lady Peng Liyuan is emerging as Chinese diplomacy's latest star.

A well-known performer on state television, the glamorous Peng featured prominently in Sunday's state media coverage of President Xi Jinping's activities in Russia. The visit is Xi's first since assuming the presidency earlier this month.

The trip, which continues this week with stops in Tanzania, South Africa, and Congo, also marks Peng's debut in her new role as first lady. Though known for her performances and volunteer work with the World Health Organization, Peng largely receded from public life after Xi was made heir-apparent in 2007.

Peng cuts a very different figure from past Chinese first ladies, who were mostly invisible at home and attracted little attention while accompanying their husbands on state visits abroad.