By-elections for the Tenth Legislative Yuan were held in 2023, one each on 8 January and 4 March, in Taiwan to elect 2 of the 113 members of the Legislative Yuan for the remaining term until 2024. The Democratic Progressive Party flipped a seat from the Kuomintang in Nantou II, and the KMT retained its seat in Taipei III. After the DPP's victory in Nantou II, Frida Tsai would become the first DPP legislator to serve a district in Nantou County since the 2005 constitutional amendment halving the number of legislative seats from 225 to 113.

Frida Tsai is a Taiwanese activist and politician. She served in the Legislative Yuan from 2016 to 2020, contested the Nantou County magistracy later that year, and in 2023, was reelected to the Legislative Yuan. She lost election the following year to Yu Hao.