Kilroot and Ballylumford power stations are being sold to the Czech firm Energetický a Průmyslový Holding (EPH).
EPH is controlled by the billionaire Daniel Kretínský and owns energy assets across Europe, including four power stations in England.
The Northern Ireland power stations are being sold by the US firm AES.
AES said the deal is part of a wider disposals strategy which also involves selling three plants in Jordan.
It will receive a total of $211m (£163m) from the sales.
The future of Kilroot and Ballylumford has been uncertain in recent years.
Kilroot, near Carrickfergus, uses relatively old and inefficient coal-fired generation.
Currently it is expected to face closure by 2024 as the coal-burning technology would not meet environmental standards.
In 2018, Kilroot lost out in a capacity auction process to supply the all-island Single Electricity Market (SEM).
It looked to be facing immediate closure but got a reprieve after an agreement was hammered out between AES, the Utility Regulator and the operator of the grid, SONI.
Ballylumford, which is Northern Ireland's largest power plant, uses gas generation.
A contract relating to part of its operations was also not renewed in 2018 and about 80 jobs will be lost as a result.
In recent year EPH has been a major buyer of coal and gas-fired power stations across Europe, often at knockdown prices.
In 2017 Mr Kretínský explained the company's strategy in an interview with the Financial Times.
He said EPH was interested in buying plants "at a meaningful price" that would continue to play at least a "midterm role."
He added that "for the next at least 10, probably 20 years", European countries will still rely on fossil fuel generation as well as renewable energy sources.