Thomas, the world number three, was heard using the derogatory word towards himself after missing a par putt on the fourth hole at Kapalua last weekend.
The 27-year-old later apolgised for the remark. He told the Golf Channel: “There’s just no excuse. I’m an adult, I’m a grown man. There’s absolutely no reason for me to say anything like that. It’s terrible. I’m extremely embarrassed.”
But Ralph Lauren this weekend announced it had severed ties with the golfer.
In a statement, the American clothing brand said: “We are disheartened by Mr Thomas’s recent language, which is entirely inconsistent with our values.
“While we acknowledge that he has apologised and recognises the severity of his words, he is a paid ambassador of our brand and his actions conflict with the inclusive culture that we strive to uphold.
“In reflecting on the responsibility we have to all of our stakeholders, we have decided to discontinue our sponsorship of Mr Thomas at this time.”
Thomas is expected to be fined for by the PGA Tour for the incident.
The PGA Tour said in a statement: “As he expressed after his round, we agree that Justin’s comment was unacceptable.”
In March last year, PGA Tour player Scott Piercy was dropped by his sponsors after sharing a homophobic meme on Instagram about former South Bend mayor Pete Buttigieg, who was a candidate for the 2020 Democratic presidential nomination.