Clarkson, who was the talent show's first winner in 2002, came out on top of a success list after pulling in a whopping $8 million (£5 million) over a 12-month period, beginning in May, 2011.
Fellow champion Carrie Underwood shared second place with rocker Chris Daughtry with earnings of $5 million (£3.1 million), while country singer Scotty MCCreery came in third with $4 million (£2.5 million).
Dreamgirls star Jennifer Hudson was fourth after surprisingly only raking in $3 million (£1.9 million) and Jordin Sparks rounded out the top five with a modest $2 million (£1.2 million).
Other singers to make the top 10 include Adam Lambert, Katharine MCPhee, Kellie Pickler, David Archuleta and David Cook.
Clarkson's latest triumph caps off an amazing month for the star - she became engaged to boyfriend Brandon Blackstock at Christmas (Dec12) and performed at U.S. President Barack Obama's inauguration ceremony.