[3] The line is one of the two services on the Express Rail Link (ERL) system, sharing the same tracks as the KLIA Transit.

At KL Sentral, the two platforms of the ERL are accessed from different parts of the station building.

[citation needed] The KLIA Ekspres side platforms are accessed from the KL City Air Terminal (KL CAT) while the KLIA Transit island platform is accessed from the main Transit Concourse at Level 1.

[5] On 24 August 2010, Express Rail Link suffered their first reported accident, in which 3 passengers were injured.

[6][7] On 4 April 2020, due to the Malaysian movement control order, which resulted in a significant reduction in ridership, all ERL rail services were temporarily suspended.

[9] Since 1 August 2023, KLIA Ekspres trains operate at a frequency of 20 minutes on all days.

The validity of purchased tickets is as follows: Electronic Payment Passengers holding AMEX, JCB, Mastercard, Visa, UnionPay contactless cards and Touch 'n Go cards may pay directly at the fare gates without the need to purchase a separate ticket.

[11] Passengers with laptops and smartphones have access to a high-speed internet connection free of charge through WiFi on board all KLIA Ekspres trains as well as on the station platforms.

The 10 millionth passenger was Emylia Rosnaida who won a business class return trip to New York City from Kuala Lumpur.

[13] The 20 millionth passenger milestone was achieved on 12 December 2007 by Mr Sockalingam, which won economy class ticket to Dubai.