Scarlet Heart (Chinese: 步步惊心, lit. Startling by Each Step) is a 2011 Chinese television series based on the novel Bu Bu Jing Xin by Tong Hua. It premiered in China on Hunan Broadcasting System (HBS) on 10 September 2011.

The series tells the story of a modern-era woman, Zhang Xiao, who time-travelled from the 21st century to the Qing Dynasty during Emperor Kangxi's reign, where she, as her previous incarnate Ma'er'tai Ruoxi, encountered the Emperor's sons, who were involved in a lengthy battle for the throne. During the course of the series, the female protagonist would meet and eventually fell in love with Fourth Prince Aisin Gioro Yinzhen, who would later on ascend the throne as Emperor Yongzheng. The plot of the series largely followed the original novel's plot, though the series's ending differed from the novel's, along with a few minor differences from both the series and novel.

A pioneer of the time slip genre in Asian television, Scarlet Heart was a commercial and critical hit, both in China and across Asia. A "sequel", Scarlet Heart 2 first aired in China on Zhejiang TV on 22 April 2014.