Disney is upping the ante for Fox, making a $71.3bn counterbid for Fox's entertainment businesses following Comcast's $65bn offer for the company.
The battle for Twenty-First Century Fox reflects a new imperative among entertainment and telecommunications firms.
They are amassing ever more programming to better compete with technology companies such as Amazon and Netflix for viewers' attention - and dollars.
The bidding war comes after AT&T bought Time Warner for $81bn, after a federal judge rejected the government's antitrust concerns.
Disney's move had been expected ever since Comcast's bid, which was higher than Disney's original offer in December of $52.5bn in stock.
After six months of integration planning we're even more enthusiastic and confident in the strategic fit of the assets and the talent at Fox
Comcast's offer was all cash. Disney's new offer of $38 per share is half cash and half stock.
In a statement, Disney said it is raising its offer because Fox's value increased due to "tax reform and operating improvements". It did not mention Comcast's bid.
"After six months of integration planning we're even more enthusiastic and confident in the strategic fit of the assets and the talent at Fox," said Disney chief executive Bob Iger in a statement.
The deal would include Fox film and TV studios, some cable networks and international assets, but not Fox News Channel or the Fox television network.
Fox chief executive Rupert Murdoch said the company "firmly believes" that the combination with Disney is a good fit.
"We remain convinced that the combination of 21CF's iconic assets, brands and franchises with Disney's will create one of the greatest, most innovative companies in the world," he said in a statement.
But the company also said it is still weighing up both offers, and noted that Disney's new bid does not have any provisions in it that prevent Fox from considering other offers.
Fox and Disney shareholders had been scheduled to vote on Disney's original bid on July 10, but that meeting has been postponed.