Ironbridge Power Station, in Shropshire, opened in 1969 and became one of the UK's largest plants.
The power station was switched off on Friday afternoon, when it reached its 20,000 hours limit of generation under an EU directive.
About 130 workers are at the site, some of whom will be kept on until 2017 to help with the decommissioning process.
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Former engineer Mike Smith pressed the button to end production.
Mr Smith, who started at the station when it first opened and retired from Ironbridge in 1992, said it was "a great honour" to have been involved with the plant.
"Obviously many people will have mixed emotions today, but I'm proud to have contributed to the success of a power station which has been at the cornerstone of energy generation and has supported the careers of many members of staff for so many years," he said.
A mosaic designed and created by pupils from St Martin's Modern School in Oswestry in 1966, which was displayed in the main conference room, will be returned to the school.
No further decisions on the future of the site will be made until the decommissioning process is completed in 2017.
E-On chief executive Tony Cocker thanked workers at Ironbridge for keeping the power station operational for decades.
"The closure of such an iconic plant will of course be tinged with sadness having played such an important role in the community," he said.
"Our continued focus will be supporting those colleagues who are directly affected by today's closure."

Wolecki Black, 50, was taken by ambulance to Victoria Hospital in Kirkcaldy.
The former Glasgow City head coach took over from Gary Bollan in December after the latter had joined Forfar Athletic.
Airdrie thanked their physio Kirsty Hughes and Cowdenbeath "for their prompt and professional response".
Former Montrose player and manager Wolecki Black had initially joined Airdrie in September as director of coaching.
That followed a spell working with Edusport Academy - a Scotland-based football academy for young French players - and a highly successful period in charge of Glasgow City.
City won four successive Scottish Women's Premier League titles during Wolecki Black's time in charge and also reached the Uefa Women's Champions League quarter-finals for the first time in 2014.
Airdrie's 3-1 win at Cowdenbeath's Central Park moved them up to fourth in Scottish League One, just inside the promotion play-off zone.
An historic power station has stopped generating electricity after more than 45 years of energy production.
[NEXT_CONCEPT]
Airdrieonians manager Eddie Wolecki Black is in a stable condition after taking ill during half-time of Saturday's win at Cowdenbeath.