Michael paid Goss a generous monthly allowance before they split in 2011 and left nothing to him after his death.
The former art dealer says he gave up his career to look after the Wham! singer during their 13-year relationship and insists Michael was “not in his right mind” when he made his will.
The businessman filed court papers against Michael’s lawyers, titled Goss v Organ.
Goss is suing under the Inheritance (Provisions for Family and Dependants) Act 1975.
George Michael left the majority of his 127 million dollars to his sisters, his dad, and a few other friends, but not his ex-partners Kenny Goss and Fadi Fawaz.