The following table shows all Legislative Assembly electorates to be contested at the 2021 state election, ordered according to two-party-preferred margin.
| Labor Seats | Liberal Seats | ||
| Seat | Margin | Seat | Margin |
| Joondalup | ALP 1.0% | Hillarys | LIB 0.1% |
| Kingsley | ALP 1.2% | Dawesville | LIB 0.9% |
| Murray-Wellington | ALP 1.8% | Geraldton | LIB 1.3% |
| Jandakot | ALP 2.0% | Darling Range | LIB 3.5% |
| Pilbara | ALP 2.3% | Riverton | LIB 4.4% |
| Kalamunda | ALP 2.4% | Scarborough | LIB 5.8% |
| Bicton | ALP 3.5% | Kalgoorlie | LIB 6.2% |
| Baldivis | ALP 3.7% vs IND | South Perth | LIB 7.2% |
| Mount Lawley | ALP 4.0% | Nedlands | LIB 8.1% |
| Burns Beach | ALP 4.3% | Bateman | LIB 8.2% |
| Albany | ALP 5.9% | Carine | LIB 10.6% |
| Balcatta | ALP 7.9% | Churchlands | LIB 11.7% |
| Southern River | ALP 7.9% | Cottesloe | LIB 14.1% |
| Wanneroo | ALP 8.9% | Vasse | LIB 14.7% |
| Forrestfield | ALP 9.4% | ||
| Landsdale | ALP 9.7% | ||
| Bunbury | ALP 11.1% | ||
| Belmont | ALP 11.4% | ||
| Swan Hills | ALP 11.9% | ||
| Morley | ALP 12.5% | ||
| Perth | ALP 12.6% | ||
| Midland | ALP 12.8% | ||
| Kimberley | ALP 13.0% | ||
| Collie-Preston | ALP 13.6% | ||
| Cockburn | ALP 13.7% | ||
| Thornlie | ALP 15.8% | ||
| Victoria Park | ALP 16.3% | ||
| Cannington | ALP 17.9% | ||
| Maylands | ALP 17.9% | ||
| Mandurah | ALP 18.1% | ||
| Willagee | ALP 18.1% | ||
| West Swan | ALP 19.2% | ||
| Butler | ALP 20.5% | ||
| Kwinana | ALP 21.0% | ||
| Bassendean | ALP 21.7% | ||
| Fremantle | ALP 23.1% | North West Central | NAT 10.1% vs ALP |
| Mirrabooka | ALP 23.5% | Warren-Blackwood | NAT 12.9% vs ALP |
| Rockingham | ALP 23.6% | Roe | NAT 13.6% vs LIB |
| Warnbro | ALP 23.7% | Moore | NAT 14.7% vs LIB |
| Armadale | ALP 25.2% | Central Wheatbelt | NAT 23.5% vs ALP |