The Good Morning Britain host did not break any rules by criticising Christian magistrate Richard Page, Ofcom said.
Last month the regulator received 70 complaints following an interview between the pair.
Mr Page was being questioned about his views on same-sex couples adopting children after he was sacked as a magistrate for saying that placing the child in the care of a same-sex couple would be in its interest.
Asked by Mr Morgan if he agreed with same-sex marriage Mr Page said no.
"So, you're a homophobe then?" Said Mr Morgan.
Complaints claimed the comment suggested any Christian who did not believed in same sex marriage was homophobic.
But Ofcom rejected this and in a statement said: "We assessed a number of complaints that Piers Morgan's tone was offensive and discriminatory towards Christians in an interview.
"We noted that the interviewee was given several opportunities to respond. He stated he was not homophobic, and set out reasons why. Overall, the interview was balanced and we found no evidence of discrimination."
