大功告成

dàgōnggàochéng
  1. successfully accomplished (project or goal)
  2. to be highly successful

CEDICT

  1. (of a project, work, etc.) to be accomplished; to be crowned with success
  2. to be accomplished; to be crowned with success

Wiktionary

艰钜、伟大的事务完成了。《儿女英雄传．第三三回》：「那失迷的失迷不了，那隐瞒的隐瞒不住了，这件事可就算大功告成了。」也作「大工告成」、「大功毕成」。

重編國語辭典

艰巨、伟大的事务完成了

維基詞典

Entry Composition

1 大功 dàgōng
  1. great merit
  2. great service
2 告成 gàochéng to declare a completion