Disney has increased its offer for 21st Century Fox to $71.3bn in cash and shares, up from an earlier $52bn offer.
The move values Fox at $38 a share, some $10 higher than Disney's first offer in December.
Disney is locked in a battle with US media conglomerate Comcast, which has offered $65bn in cash for Fox.
"The acquisition of 21st Century Fox will bring significant financial value to the shareholders of both companies," said Disney boss Robert Iger.
The improved offer came as 21st Century Fox board was set to decide whether to back Comcast's bid for assets that include Fox's film and television studios and international businesses.
Disney also wants to acquire those businesses. The two firms are also vying for ownership of Sky in the UK.
Fox said it would now allow shareholders to evaluate Disney's amended offer.
Disney's latest offer is "superior" to the proposal made by Comcast, Fox said in a statement.
In pre-market trading, Fox shares rose 5.4% to $47.11, Comcast's were marginally lower, while Disney's rose by 1.3% to $107.50.
Any takeover by either Disney or Comcast would be likely to face regulatory scrutiny.
The US government is currently suing to block a merger between Time Warner, and the telecoms giant AT&T.
The fight for 21st Century Fox comes as traditional media groups scramble to consolidate in the face mounting competition from online challengers like Netflix and Amazon.
It has driven broadcast giant CBS to try to merge with Viacom, which owns the MTV and Nickelodeon television stations.
It has also spurred AT&T's $85.4bn offer for Time Warner, whose assets include pay TV channel HBO.
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