| Competition: | League of Ireland |
| Season: | 1942–43 |
| Winners: | Cork United (3rd title) |
| League Topscorer: | Seán McCarthy (16 goals) |
| Biggest Home Win: | Limerick 7–0 Bray Unknowns |
| Biggest Away Win: | Bohemians 0–5 Shelbourne Bray Unknowns 0–5 St James's Gate Bray Unknowns 0–5 Dundalk |
| Highest Scoring: | Bray Unknowns 5–4 Brideville |
| Matches: | 90 |
| Total Goals: | 339 |
| Prevseason: | 1941–42 |
| Nextseason: | 1943–44 |
The 1942–43 League of Ireland was the 22nd season of senior football in the Republic of Ireland. Cork United were the defending champions.
No new teams were elected to the League.
Cork United won their third title, becoming the first team to win three consecutive titles.