Attorney Peter Sample said the allegations are completely false, reported The Wrap.
"The allegations against Ms Heard are absolutely and unequivocally false. The claim that she is blackmailing Johnny "has no basis in reality and is nothing but the typical celebrity muckraking for profit," Sample said.
The lawyer also said that the claims against Heard, 30, are defamatory and "outrageous."
While Depp has not directly addressed the accusations made by Heard, his representative released a statement shortly after the couple filed for divorce.
Depp's family has come to his defense against Heard, with daughter Lily-Rose Depp, calling him the "sweetest, most loving person I know" on Instagram.
Her mother, actor's ex-partner of 14 years Vanessa Paradis, also reportedly wrote a letter supporting him.