Environment Minister Leona Aglukkaq says the funding comes on top of $1.2 billion in Canadian contributions to what is known as the Fast-Start Financing Initiative.
That money goes to projects focused on climate-change adaptation and increasing renewable energy in more than 60 developing countries.
The latest contribution comes as the Harper government is under opposition pressure over its ability to meet greenhouse gas targets.
Aglukkaq says the government is committed to establishing a fair international climate change agreement at a major conference in Paris next year.
Canada wants all major greenhouse gas emitters to agree to binding obligations in that agreement.
The minister said the green fund's help for the poorest countries will play a key role in addressing climate change.
She said the government will continue to seek a balanced approach on the issue.
"We will continue to protect our environment and support our economy as we move towards a new climate agreement in 2015 that must include all major economies and major emitters."
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