Steam at the terminus began to decline further with the pushing through of the Kent Coast Electrification, having first seen serious culls during the SR suburban electrification of the 1920s. The turntable at Belvedere Road, on the South Bank, was removed as early as 1951, but locomotive facilities were still on offer adjacent to Southwark Depot, at Ewer Street. Six years later, Hastings DEMUs began arriving in force, these taking over from Schools class locomotives and Maunsell carriages on the route via Tunbridge Wells Central. With electric working commencing from Charing Cross to Dover on 12th June 1961, the steam age at London’s most centrally located station was over. For many years after the end of steam, and the cessation of the ''Man of Kent'' working, locomotives in general were banned from the terminus, only those diesels with a Bo-Bo wheel arrangement being permitted over Hungerford Bridge. Although a batch of ''Hastings'' DEMUs had been produced with reduced-length carriages to accommodate a locomotive when stabled in the terminal platforms, this subsequently never occurred, and Charing Cross became regarded by British Rail as a terminus which had difficulty in dealing with locomotive-hauled services.
Meanwhile, improvement of electric services for the ‘’suburban’’ side of the terminus had come along swimmingly. With Bulleid’s Double-Decker trains being deemed unsuccessful, it was decided to alleviate overcrowding on the North Kent Lines by creating EPB formations of ten vehicles in length. This required the extension of platforms on all routes, the intermediate ones being treated with prefabricated concrete. Only platforms 1 to 3 at Charing Cross required extension, wood being used throughout, which in itself required revision of the track work. The terminus received its first scheduled ten-car formations from the youngest of the North Kent routes, that via Bexleyheath, from 14th June 1954. The Dartford Loop Line via Sidcup followed on 13th June 1955, and the oldest route of them all, the ‘’North Kent Line’’, served ten vehicle formations from 17th June 1957.
The SR’s 1926 colour light system was planned for replacement during the 1970s. Mechanical signal boxes which still existed on many of the South Eastern Division’s suburban lines were to be superseded by far fewer, and more advanced, electronic centres. Indeed, it was on 16th April 1976 that Charing Cross’ cabin, which was suspended above the tracks at the ends of the platforms, was taken out of use. The London Bridge Panel assumed its functions – most of the mechanical cabins on the North Kent routes had previously been decommissioned in 1970, with the opening of the Dartford Panel and a temporary signalling arrangement at St Johns. Signalling modernisation was followed in 1979 by the rebuilding of the existing 1864 section of Hungerford Bridge, which took until 1980 to complete and required the closure of the suburban platforms for half a year.
The 1980s saw some big changes. In 1985, the trainshed frame was repainted from unassuming grey, into bright red, reflecting the colours of the 1982-established London & SouthEast sector. Concurrent with this, the Southern Railway crest which still existed on the trainshed’s river side façade, was replaced with a longer lasting fibreglass equivalent. Unfortunately, the existence of the 1906 ridge-and-furrow roof was to be terminated as plans, which would transform the station beyond recognition, were pushed through. In 1988, work began on dismantling the trainshed to make way for thousands of tonnes worth of office block, supported above the platforms by a succession of thick columns. Costing £130,000,000, it was not, however, the first such scheme, a similar concept having nearly been realised in 1963. The latter had outlined the removal of the concourse roof to allow for the adjacent hotel to be further extended, towards the buffer stops. Suspended over the platforms were proposed an array of offices and retail outlets, but the scheme was unsuccessful in being granted planning permission. With reference to the 1988 project, the platforms were to become gloomy and claustrophobic, with much vintage character disappearing, but at least passenger facilities were to see improvement. Strengthening of buildings adjacent to the station had occurred during 1987. Whilst most of the 1906 ridge-and-furrow trainshed roof was dismantled to accommodate the office block colossus, interestingly the rear two spans of this structure - immediately adjacent to the existing concourse roof - were retained as part of an enlarged waiting area. The office block over the platforms opened in 1992, although it would be until 1998 that re-glazing of the concourse and restoration of the hotel's façade was finished. It was during the construction of the office block that the terminus once again saw locomotives, in the form of Class 33s on departmental workings.