The 2018–19 season was Charlton Athletic's 113th season in their existence. Along with competing in the League One, the club also participated in the FA Cup, EFL Cup and EFL Trophy. The season covered the period from 1 July 2018 to 30 June 2019.
On 22 May 2018, Charlton Athletic announced its first confirmed friendly taking place ahead of the 2018–19 season would be against Welling United at Park View Road.[50] On 29 May the first home friendly was announced which would see Brighton & Hove Albion visit The Valley on 24 July 2018.[51] A further home friendly was added against Norwich City for 28 July 2018.[52] On 27 June 2018 it was announced that a behind-closed door friendly between Queens Park Rangers and Charlton Athletic would take place on 7 July at QPR's Harlington training ground.[53]