To pull off or accomplish something difficult or impressive; colloquial and emphatic.
彼女は短期間で新しいシステムを構築して、見事にやってのけた。
She built the new system in a short time and pulled it off brilliantly.
あの選手が故障を乗り越えて優勝したとき、本当にやってのけたと思った。
When that athlete overcame injuries and won, I really thought he had pulled it off.
簡単にはできない仕事を彼らがやってのけたのは驚きだ。
It's surprising that they managed to carry out a job that wasn't easy.
最初は無理だと思われていたが、チーム全員でやってのけた。
At first it seemed impossible, but the whole team pulled it off.