It will cut its reliance on the fuel to 29 per cent of its electricity needs by 2035.
Nuclear energy currently accounts for 30 per cent of electricity generation, and the original plan was to raise that figure to 41 per cent by 2035.
The Ministry of Trade, Industry and Energy said it has accepted recommendations from a government advisory group in September to scale back the nuclear expansion plans.
Safety concerns that were already high in the wake of the 2011 Fukushima crisis in Japan have been heightened by revelations of widespread corruption and faulty equipment.
Nuclear reactors have been abruptly shut down 128 times over the past decade because of malfunctioning parts, officials admitted in October.
Public prosecutors have charged about 100 people after discovering that documents relating to some parts in 20 working reactors, and eight under construction, had been forged.
The country has 23 reactors, while five reactors are under construction and six more have received planning approval.
The ministry said nuclear reactors will continue to play a key role in South Korea's energy mix but did not confirm how many would be built by 2035.
Electricity consumption is expected to grow an average of 0.9 per cent every year, the ministry said, vowing to reduce consumption through price rises and other measures.