| Election Name: | 1919 Widnes by-election |
| Type: | presidential |
| Country: | United Kingdom |
| Previous Election: | Widnes (UK Parliament constituency)#Elections in the 1910s |
| Previous Year: | 1918 |
| Next Election: | Widnes (UK Parliament constituency)#Elections in the 1920s |
| Next Year: | 1922 |
| Election Date: | 30 August 1919 |
| Candidate1: | Henderson |
| Party1: | Labour Party (UK) |
| Popular Vote1: | 11,404 |
| Percentage1: | 52.3 |
| Candidate2: | Fisher |
| Party2: | Unionist Party (UK) |
| Popular Vote2: | 10,417 |
| Percentage2: | 47.7 |
| Map Size: | 250px |
| MP | |
| Posttitle: | Subsequent MP |
| Before Election: | Walker |
| Before Party: | Unionist Party (UK) |
| After Election: | Clayton |
| After Party: | Unionist Party (UK) |
The 1919 Widnes by-election was held on 30 August 1919. The by-election was held due to the elevation to the peerage of the incumbent Coalition Conservative MP, William Walker. It was won by the Labour candidate Arthur Henderson.