Kingsnorth has stopped producing power after more than 40 years of operation.
The coal-fired power station at Hoo ceased commercial generation at 3.10pm on December 17.
Work to decommission Kingsnorth will now take place and it will formally close by March 31, 2013.
The closure leaves more than 100 employees with an uncertain future.
When it was announced in March that the plant would close the GMB union said it would be “absolutely devastating” for the local economy.
Kingsnorth, which opened in 1970, has been forced to close because of European Union legislation.
The EU’s Large Combustion Plant Directive legislation requires plants to close after generating power for 20,000 hours from January 1, 2008, or at the end of 2015, whichever comes first.
E.ON cancelled plans to build two new coal-burning units to replace the existing power station on the site in 2009.
The two units would have been fitted with carbon capture and storage (CCS).
The energy company blamed the recession and a fall in demand for electricity.
Tony Cocker, chief executive of E.ON, said: “Above all else I want to say thank you to all the men and women who built and worked at Kingsnorth throughout its lifetime.”
Mr Cocker said the move highlights the “very real and present need” for the government to come up with a plan to provide a future for other power stations and to invest in the country’s energy infrastructure.