Brookfield and GIC's offer of $112 per share represents a premium of 12% to Genesee's closing price on Friday. Genesee shares were up about 8% in trading before the bell.
Including debt, the deal is valued at about $8.4 billion, the companies said in a statement.
Genesee & Wyoming's revenue have increased at a compound annual growth rate of 16.8% since it floated in the stock market in 1996, rising to $2.3 billion in 2018 from $77.8 million, according to Genesee & Wyoming's latest annual report.
The company owns a portfolio of 120 short-line railroads, predominantly in North America, with operations in Europe and Australia.
Reuters had reported on the deal on Sunday, citing sources.
The deal, which is expected to close by year end or early 2020, would be the latest big leveraged buyout by Brookfield, which agreed last year to buy Johnson Controls International's power solutions business for about $13 billion.