The news comes after a report emerged last month claiming the 38-year-old singer had reportedly paid out US$1.1 million to a woman who he allegedly infected with the disease in 2012.
The three claim to have had sexual contact with the Yeah singer after 2012 and say that he failed to warn them that he allegedly has the STD, according to Hollywood Life.
Celebrity attorney Lisa Bloom said she is planning to file the suit in California on Monday and will hold a news conference to correspond with the filing as one of the women is set to appear with her.
The other woman and man involved in the suit will remain anonymous and will appear as Jane Doe and John Doe in the lawsuit.
In legal docs in the first case, initially published by Radar Online, Usher said he initially learned he had herpes around 2009-2010.
The woman suing the star stated that Usher said he was not infected with herpes despite a 'greenish discharge' from his genitalia, leading her to continue having sex with him.
She was eventually diagnosed with herpes, experiencing symptoms including vaginal sores, fevers and chills.