[1] From 2005 to 2018, the network was gradually electrified and expanded to serve Piraeus to the south, Corinth and Kiato to the west, and Chalcis to the north.

"Proastiakos SA" was founded in 2003 as a subsidiary of OSE to serve the operation of the suburban network in the urban complex of Athens during the 2004 Olympic Games.

However, from 2010, the electrification works of the lines with 25 kV AC, 50 Hz began to be completed, allowing the use of the Siemens Desiro 460 trains.

Athens on 30 July 2017 led to the modification of the lines of the Suburban Railway to have as a starting point the central station of the capital.

During the COVID-19 pandemic, TrainOSE provide free antiseptic gel to the passenger public in order to disinfect those who use the commuter train.

The court ruled that "the requirement of a 'photography permit' is tantamount to a ban" and that "there is no legal authority to impose restrictions on the right to photograph spaces and slides by definition accessible to the public".

[38] A nine-station, 32 km extension of the Athens Suburban Railway from Koropi to Lavrio was announced in 2016, potentially connecting 300,000 more people to the rail network at a cost of €160 million.

[44][45] The project involves the construction of two new stations at Markopoulo and Lavrio Port, and five intermediate stops at Kalyvia, Keratea, Daskaleio, Thorikos and Kyprianos.

In February 2019, OSE accepted a bid for the €12 million project to convert the former metre-gauge line between Isthmos and Loutraki to standard gauge, connect it to the Athens Airport–Patras railway and reopen it to passenger traffic by November 2021.