The list of ship commissionings in 1870 is a chronological list of ships commissioned in 1870. In cases where no official commissioning ceremony was held, the date of service entry may be used instead.
| Operator | Ship | Class and type | Pennant | Other notes | |
|---|---|---|---|---|---|
| 4 March |  United States Navy | USS Congress | Sloop | ||
| 13 March |  Colony of Victoria | HMVS Cerberus | Cerberus-class breastwork monitor | ||
| April |  Royal Navy | HMS Captain | Turret ship | [1] | |
| 28 September | Royal Navy | HMS Vanguard | Audacious-class battleship | ||
| 1 October | Royal Navy | HMS Invincible | Audacious-class battleship |