Fox Corp. is buying streaming giant Roku in a blockbuster deal valued at roughly $22 billion, including debt, creating a media powerhouse that the companies say will become the third-largest player in US television by share of viewing.

The acquisition, first reported by the Wall Street Journal, brings together Fox’s portfolio of live sports, news and entertainment programming with Roku’s streaming platform and connected-TV operating system, which reaches more than 100 million households worldwide.

Fox CEO Lachlan Murdoch touted the merger as a transformational move as competition for streaming audiences intensifies.

The deal combines “the most valuable live content portfolio in video consumption with the preeminent streaming platform,” Murdoch told investors on a conference call on Monday.

Fox Corp is sister company to The Post’s corporate parent News Corp.