The Spanish-language broadcaster recently announced it would not show the July 12 Miss USA pageant after Trump made "insulting remarks about Mexican immigrants" during a speech announcing his presidential candidacy.
When asked by ABC News last week whether he regretted those comments, Trump said, "Not at all. I said it about people from all over. I didn’t say it about Mexico – I said people from all over."
The suit, which alleges breach of contract and defamation, also claims that Univision pressured NBC to cut ties with Trump and the Miss Universe Organization on Monday.
Univision called the suit both "factually false and legally ridiculous" in a statement.
"We will not only vigorously defend the case, but will continue to fight against Mr. Trump's ongoing efforts to run away from the derogatory comments he made on June 16th about Mexican immigrants," the statement said.
Previously, the network said it sees "first-hand the work ethic, love for family, strong religious values and the important role Mexican immigrants and Mexican-Americans have had and will continue to have in building the future of our country. We will not be airing the Miss USA pageant on July 12th or working on any other projects tied to the Trump Organization."
Last week, Trump banned any employee of Univision from stepping foot on one of his properties, sending a signed letter to the company's CEO.
"Please congratulate your Mexican Government officials for having made such outstanding trade deals with the United States," Trump wrote in the letter. "However, inform them that should I become President, those days are over. We are bringing jobs back to the U.S. Also, a meaningful border will be immediately created, not the laughingstock that currently exists."