Greek National Road 9a (), abbreviated as the EO9a, is a national road in the Peloponnese region of Greece. Created in 1995, the EO9a carries the European route E55 between Tsakona and Kalo Nero.
The EO9a is officially defined as an east-west road in the Messenia regional unit, running between Tsakona and the A7 motorway to the east, to Kalo Nero and the EO9 to the west. The entirety of the EO9a is part of European route E55.
Ministerial Decision DMEO/e/oik/779/1995 of 24 July 1995 created the EO9a, and classified it as part of the secondary national road network. It is unclear when the EO9a number came into use, but the number is presently in regular use.