Lambert, runner-up of the singing competition's eighth season, earned about $10 million from a lucrative position as the band Queen's frontman during their tour last year. Forbes magazine first compiled the list, published Wednesday.
Second on the list is country singer Carrie Underwood with an $8 million paycheck. Underwood was the highest-earning American Idol alum for 2013 and 2014, and may be up for the top spot again as her latest tour kicks off at the end of January 2016.
Daughtry, the band headed by Idol winner Chris Daughtry, earned $6 million in 2015 having reportedly played 91 shows during the magazine's scoring period.
This year, American Idol launches its final season on television, its preliminary auditions featuring even famous faces like Kanye West, who performed his classic hit "Gold Digger," in front of judges.