The 1970–71 FAW Welsh Cup is the 84th season of the annual knockout tournament for competitive football teams in Wales.
League name pointed after clubs name.
Nine winners from the Fourth round and seven new clubs.
| width=50 | Tie no | width=250 | Home | width=50 | Score | width=250 | Away |
|---|---|---|---|---|---|---|---|
| 1 | Chester (FL D4) | 1–1 | Rhyl (CCL) | ||||
| replay | Rhyl (CCL) | 0–2 | Chester (FL D4) |
| width=50 | Tie no | width=250 | Home | width=50 | Score | width=250 | Away |
|---|---|---|---|---|---|---|---|
| 1 | Chester (FL D4) | 2–1 | Swansea Town (FL D3) |
| width=50 | Tie no | width=250 | Home | width=50 | Score | width=250 | Away |
|---|---|---|---|---|---|---|---|
| 1 | Cardiff City (FL D2) | 0–0 | Chester (FL D4) | ||||
| replay | Chester (FL D4) | 1–2 | Cardiff City (FL D2) | ||||
| 2 | Oswestry Town (CCL) | 0–2 | Wrexham (FL D3) |
| width=50 | Tie no | width=250 | Home | width=50 | Score | width=250 | Away |
|---|---|---|---|---|---|---|---|
| 1 | Wrexham (FL D3) | 0–1 | Cardiff City (FL D2) | ||||
| Cardiff City (FL D2) | 3–1 | Wrexham (FL D3) |