Doing something all at once and finishing it in a single, uninterrupted effort (often used for writing or work).
締め切り前にレポートを一気呵成に仕上げた。
I finished the report in one go before the deadline.
彼は会議資料を一気呵成に作り上げたので驚かれた。
He surprised people by producing the meeting materials all at once.