The power station has leaked radiation into the air, sea and land since it was crippled by the earthquake on 11 March in the world's worst nuclear disaster since Chernobyl.
Tokyo's neighbours have been concerned by the leak and its impact on food safety across the region, but Saturday's visit focused on paying respects to the lives and homes lost in the disasters.
Wen and Lee are the first foreign leaders to visit Fukushima since the disaster which left around 24,000 people dead or missing
"I came to Fukushima on my own decision," Wen told reporters. "I believe Fukushima will be restored with courage and confidence."
Wen also said Beijing was ready to ease restrictions on imports of farm produce from Japan and encourage Chinese people to travel to the country.
Meanwhile, Lee visited another evacuation centre in Natori, Miyagi prefecture, northeast of Fukushima, which was among the areas hit hardest by the disasters. He offered Seoul's support to children who have been traumatised by the disaster, and spoke of his hope that Japan will recover as quickly as possible.
The visit to Fukishima comes ahead of a three-nation summit, first held on a regular basis in 2008.
For Beijing and Tokyo, this summit is seen as their latest opportunity to mend ties following a bitter territorial row triggered by Japan's arrest of a Chinese trawler captain near their disputed islands last September.