Nea Makri is situated on the coast of the Petalioi Gulf, a gulf of the Aegean Sea, in the easternmost part of the Attica peninsula. It is 7 km north of Rafina, 8 km south of Marathon and 25 km northeast of Athens city centre. The municipal unit Nea Makri also contains the village Neos Voutzas, 5 km south of Nea Makri town centre. Greek National Road 83 (Athens - Marathon - Rafina) passes through Nea Makri.
The United States Navy operated a HF radio communications base north of Nea Makri from the mid to the late 20th century. The transmitters were located further north, at Kato Souli. The callsign of the station was NGR. The American naval communications station was the deployment location for Naval Mobile Construction Battalion 133, homeported in Gulfport, MS.