The baby news came to light when Corden asked Ferguson and another guest, Charlie Hunnam, about their experiences turning 40.
"It's when you finally become an adult I feel, I need to start getting serious about things," Ferguson replied. "Actually, this is something I haven't even mentioned to anyone if we could just keep it between the three of us and you all, but I'm actually expecting a baby in July with my husband," he said.
The Modern Family star was all smiles as the audience cheered about the secret. "I'm very excited. It feels like I'm 44 now, let's get this show going," he expressed jokingly.
Ferguson tied the knot back in 2013 and coincidentally will be celebrating his 7th anniversary the same month (July) when the baby is expected.
The Extreme Makeover: Home Edition host didn't reveal any more details, but if Ferguson is anything like his TV persona, then we can't wait to see his fathering skills in action.