The Wall Street Journal reports that the former mayor's foundation Bloomberg Philanthropies will announce the gift today.
Some 12,000 children drown in Bangladesh every year.
The Journal says the gift will be included in a letter that will provide insight into Bloomberg's priorities as a philanthropist.
In the letter, the billionaire businessman writes that he now has more time to spend on national and global issues. He says he plans to "substantially expand" his foundation's work. Bloomberg Philanthropies has some USD 4.2 billion in assets and distributed USD 452 million in 2013.