| Election Name: | 1923 Portsmouth South by-election |
| Type: | presidential |
| Country: | United Kingdom |
| Previous Election: | 1922 Portsmouth South by-election |
| Previous Year: | 1922 |
| Next Election: | Portsmouth South (UK Parliament constituency)#Elections in the 1920s |
| Next Year: | 1923 |
| Election Date: | 13 August 1923 |
| Candidate1: | Cayzer |
| Party1: | Unionist Party (UK) |
| Popular Vote1: | 11,884 |
| Percentage1: | 54.9 |
| Candidate2: | Lawson |
| Party2: | Liberal Party (UK) |
| Popular Vote2: | 9,763 |
| Percentage2: | 45.1 |
| Map Size: | 250px |
| MP | |
| Posttitle: | Subsequent MP |
| Before Election: | Wilson |
| Before Party: | Unionist Party (UK) |
| After Election: | Cayzer |
| After Party: | Unionist Party (UK) |
The 1923 Portsmouth South by-election was a parliamentary by-election held in England on 13 August 1923 to elect a new Member of Parliament (MP) for the House of Commons constituency of Portsmouth South in Hampshire.
The seat had become vacant when the constituency's Conservative MP Leslie Orme Wilson had been appointed as Governor of Bombay, and had therefore resigned from the Commons on 26 July by the procedural device of accepting appointment as Steward of the Manor of Northstead. Wilson had held the seat for less than a year, having won it at a by-election in December 1922.[1] He had previously been the MP for Reading from 1913 to 1922.
The result at the last election was
Cayzer was re-elected for Portsmouth South at the next five general elections, and held the seat until he was ennobled in 1939. Lawson never stood for Parliament again. The result at the following general election;
. F. W. S. Craig . British parliamentary election results 1918–1949 . 1969 . 3rd . 1983 . Parliamentary Research Services . Chichester . 0-900178-06-X . 219.