Ko Chia-Yen (Chinese: 柯佳嬿; pinyin: Kē Jiāyàn; born 10 January 1985) is a Taiwanese actress.

Ko's debut acting role was in the 2006 film Do Over, by award-winning director Cheng Yu-chieh. Subsequently, she had starring roles in the films Miao Miao (2008), Monga (2010) and Night Market Hero (2011). She first came to prominence for her role in the domestic hit series Office Girls (2011), in which she played a marketing specialist. She is also known for her role in the drama series Marry Me, or Not?, for which she won the Golden Bell Award for Best Actress in 2016.