The Championship Play-Off Final between Reading and Swansea City is worth £90m for the winner, according to accountancy group Deloitte.
The figure of £90m includes over £40m from broadcast income plus increased gate receipts and commercial income. If the club were immediately relegated as last year's Play-Off Winners Blackpool were then, they would also get payments of up to £48m.
Paul Rawnsley, director of the Sports Business Group at Deloitte, said to the BBC: "In financial terms, the Championship play-off final offers the winning club the most substantial prize in world football.
"Promotion offers an unparalleled, and potentially one-off, opportunity to strengthen the foundations of a club for years to come, through sound investment in long-term infrastructure, in addition to the expected player acquisitions in the short term."