By-elections for the Ninth Legislative Yuan were held in 2019, two on 27 January and four on 16 March, at Taiwan to elect 6 of the 113 members of the Legislative Yuan for the remaining term until 2020.
The by-election was the result of resignations by Pasuya Yao, Democratic Progressive Party legislator for Taipei 2; Kuomintang legislator Lu Shiow-yen from Taichung 5; Wang Huei-mei, Kuomintang legislator for Changhua County 1; Huang Wei-cher, Democratic Progressive Party legislator for Tainan 2; and Yang Cheng-wu, Kuomintang legislator for Kinmen County.
All but Yao won election to local offices in the 2018 local election. Under the Article 73 of the , if any positions become vacant due to resignation or election to another office, and the vacated term is longer than one year, a by-election shall be completed within three months commencing from the date of resignation.
On 30 November 2018, the Central Election Commission announced that by-elections for Taipei 2 and Taichung 5 were to be held on 26 January 2019. On 4 December 2018, the CEC moved the date to 27 January 2019, as the previously announced date coincided with the General Scholastic Ability Test. Registration of candidacies for these two seats were open from 10 to 14 December 2018.
By-elections for vacant seats in Changhua County 1, Tainan 2, Kimnen County and New Taipei 3 were scheduled for 16 March 2019.
Voted on 27 January 2019.
Voted on 27 January 2019.
Voted on 16 March 2019.
Voted on 16 March 2019.
Voted on 16 March 2019.
Voted on 16 March 2019.