大功告成

dà gōng gào chéng

mission accomplished

Character by character

大dà
great

功gōng
work

告gào
declare

成chéng
complete

最后一块拼图放好，大功告成！

Last jigsaw piece in place — done!

Tone: positive (praise).

Often a cheerful announcement on finishing something.

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This idiom and thousands more are in Learn Chinese with Bao, with audio, pinyin and drills that make them stick.