American billionaire Paul Singer’s Elliott Management Corp. promised an initial €50 million ($58.7 million) cash injection into Italian soccer team AC Milan, providing a much-needed lifeline to the storied team that is fighting a sanction that would keep it out of the Europa League this season.

AC Milan’s new owner said Tuesday that the equity capital—and promises for more down the road—should stabilize the seven-time European champion financially.

“Financial...