Appearing at the Billboard Latin Music Awards ceremony Thursday, Martin said the law "makes no sense," and he urged an end to discrimination, hate and racism.
"Long live love, long live peace," he told the audience at the award show in San Juan, Puerto Rico.
Martin received a standing ovation when he walked on stage, making one of his first public appearances since announcing he is gay.
"This is not in the script," he said as he launched into his criticism.
"You are not alone. We are with you," Martin said. "Put a stop to discrimination. Put a stop to hate. Put a stop to racism."
Mexican pop singer Paulina Rubio also criticized the law, as did Larry Hernandez, who won Latin Artist of the Year and said he began his career in Phoenix.
"It's regrettable that they are discriminating against us for the simple fact of looking Latino. It's not fair. We have to say no to that law," Hernandez said.
Caption: Puerto Rican singer Ricky Martin speaks at the 2010 Billboard Latin Music Awards in San Juan, Puerto Rico, Thursday, April 29, 2010. Ricky Arduengo / AP Photo