List of ship commissionings in 1931
The list of ship commissionings in 1931 includes a chronological list of all ships commissioned in 1931.
| Operator | Ship | Flag | Class and type | Pennant | Other notes | |
| 21 March | ' | VN | ||||
| 20 July | ' | O 12 | ||||
| 28 July | ' | O 15 | ||||
| 1 October | ' | O 13 | ||||
| Uncertain | ' | C-1 | acquired from Italy | |||
| Uncertain | ' | C-2 | acquired from Italy |