List of 2009–10 League of Ireland transfers

This is a list of transfers involving clubs that played in the 2010 League of Ireland Premier Division and 2010 League of Ireland First Division.

The pre-season transfer window opened on 1 December 2009, and closed on 22 February 2010 for domestic transfers, and on 2 March 2010 for foreign transfers. Players without a club may join one at any time, either during or in between transfer windows.