In 1979 Hsiao began party work, serving in turn as the Assistant Director of the Department of Organization Affairs, Director of the Department of Social Affairs, and Vice-Secretary General of the Policy Coordination Committee (all of these being sub-units of the Kuomintang Central Committee).
「每個星期有三天深夜，是在嘉義往台北的末班莒光號上度過」，蕭天讚認為自己的立委生涯是「傳聲筒」。魚與熊掌難得兼六十八年，蕭天讚開始參與黨務工作。他先後出任執政黨中央組工會副主任、中央社工會主任、中央政策會副秘書長。