Timothy Trybus, of Des Plaines, wept when the verdict was announced.
The 63-year-old was brought to trial after confronting Mia Irizarry on June 14, 2018, at Caldwell Woods, a Chicago forest preserve.
In a cellphone video recorded by Irizarry, a man identified as Trybus questioned her citizenship and continued to harass her, authorities said.
"You should not be wearing that in the United States of America," he told her.
Puerto Rico is a U.S. commonwealth.
Prosecutors said Trybus appeared to be drunk.
“Being drunk, being intoxicated in no way excuses the defendant in what he did,” Assistant State’s Attorney Patricia Berlinsky said, according to The Chicago Sun-Times.
The incident also prompted criticism of a Cook County Forest Preserves officer who witnessed what was happening but didn't respond when Irizarry asked for help.
Irizarry, 25, testified Tuesday that she feared for her safety. She declined to comment after the verdict.
Prosecutors said although Trybus never touched Irizarry, his verbal barrage and aggressive manner were motivated by the Puerto Rican flag on her shirt -- constituting a hate crime.
Trybus was initially charged with misdemeanor assault, but the charges were amended following complaints from the city's Puerto Rican community.
He faces probation to five years in prison when he is sentenced in October.
The Associated Press contributed to this report.