The move will bring together the separate entities with both firms holding a 50% stake in the new venture.
The chair position will be rotated between the two companies, with the inaugural post held by Marc Allera, CEO of BT’s consumer division.
Allera said: “As we enter our ninth season, today is day one of an exciting new chapter for BT Sport.
“I am extremely proud of the teams and the established brand and broadcaster that BT Sport has become, and I look forward to working with Warner Bros. Discovery to create an exciting new sport TV offering for the UK.”
The JV received approval for the JV in July after a deal was agreed upon in May.
The deal will include rights to the UEFA Champions League, Premier League and Olympic games as well as Eurosport staples such as winter sports world cups, cycling grand tours and tennis Grand Slams.
Andrew Georgiou, Warner Bros. Discovery Sports Europe President and MD, said today “marks the start of our journey to build a new sports destination for fans in the U.K and Ireland.”
Georgiou will sit on the board chaired by Allera.