A colloquial contraction of 'やるしかない,' meaning there is no choice but to do it — used in spoken Japanese to express resigned determination.
締め切りが明日だから、やるっきゃないね。
The deadline is tomorrow, so we've got no choice but to do it.
計画が変わったけど、やるっきゃないとチームに伝えた。
The plan changed, but I told the team we have no choice but to go ahead.
失敗したらどうしようと思ったが、やるっきゃないと決心した。
I worried about failing, but I decided there's nothing else to do but try.