List of ship decommissionings in 1940
The list of ship decommissionings in 1940 is a chronological list of ships decommissioned in 1940. In cases where no official decommissioning ceremony was held, the date of withdrawal from service may be used instead. Notably, several destroyers were decommissioned by the United States Navy during 1940 for immediate transfer to the Royal Navy under the Destroyers for Bases Agreement between the two nations. For ships lost at sea, see list of shipwrecks in 1940 instead.
| Date | Operator | Ship | Class and type | Fate and other notes | Ref |
| 9 September | ' | decommissioned at Halifax and transferred to the Royal Navy | |||
| 9 September | ' | decommissioned at Halifax and transferred to the Royal Navy as HMS Clare | |||
| 23 September | ' | decommissioned at Halifax and transferred to the Royal Navy | |||
| 11 October | ' | transferred to the Royal Navy | |||
| 11 October | ' | transferred to the Royal Navy | |||
| 11 October | ' | transferred to the Royal Navy | |||
| 26 November | ' | transferred to the Royal Navy | |||
| 26 November | ' | transferred to the Royal Navy |