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 |