Kamen caught the eye in a 1985 Levi's jeans advert - baring his chest in a launderette - and the queen of pop invited him in on a track the following year. He died this week aged 59.
"Heartbreaking to know you are gone," the superstar posted online.
The pair had a top five hit with Each Time You Break My Heart, which featured Madonna on backing vocals.
"You were always such a kind, sweet human and you suffered too much," she added.
"Hope you are happier wherever you are Nick Kamen."
Kamen - real name Ivor Neville Kamen - rose to fame in the Levi's commercial, which showed him stripping down to his boxer shorts in a launderette as several women looked on.
The advert, soundtracked by Marvin Gaye's I Heard It Through The Grapevine, helped to boost the company's denim sales and made him a sex symbol in the process.
It also caught the attention of Madonna, who told the BBC at the time she had been taken by Kamen's "charisma" and "beautiful voice".
She then contacted Kamen and asked him to record Each Time You Break My Heart - a synth-pop track left over from her third album True Blue.
From BBC News
It breaks my heart to know you are gone. You were always such a kind sweet human and you suffered too much. Hope you are happier wherever you are Nick Kamen. 🙏🏼 pic.twitter.com/Cfk8vkM1Je— Madonna (@Madonna) May 5, 2021