LONDON — Southampton secured an immediate return to the Premier League on Sunday by beating Leeds 1-0 at Wembley Stadium in the Championship playoff final, the richest one-off match in world soccer.

An uplift of 140 million pounds ($180 million) in future earnings from broadcast revenue and prize money is guaranteed for the south-coast club thanks to Adam Armstrong’s 24th-minute winner at England’s national stadium.

Southampton is heading back up to the lucrative Premier League alongside…