Josh, 44, and Yessica were previously just parents to little girl named Java, who was born April 2009, and confessed they had expanded their brood this year, after sharing they had another child on the way last November
"Yes we have!" Josh shared with E! News at the Los Angeles PaleyFest reunion for his show this week. "Six-week-old boy, Hunter Lee Holloway."
The screen star credited his partner with making sure he was getting enough sleep at night despite having another youngster on his hands.
He joked that he'd be nothing without the great mother - who he had almost been married to for a decade - taking care of him and his children.
"Yes, my wife's a rock star," he shared. "I'm a loser, just ask her. I'm kidding. It's all good."
Josh also spoke about his Lost character Sawyer likely relying on a woman to make sure everything was in order if the programme was to have continued past May 2010.
"Whatever it is he'd be doing, it would probably be with a woman," he laughed. "He tends to lean that way in all his operations. So I'd say that."
In a previous interview with Entertainment Tonight, he responded to a question about being a TV sex symbol by saying that he's actually all about being a great partner and parent.
The comment was the first time the public had been made aware of his wife's pregnancy.
"That's funny because I'm a family man. I've got a four-and-a-half-year-old daughter and another one on the way. Pretty excited about that," he quipped.
Josh proposed to Yessica while shooting the pilot of Lost in Hawaii, and they tied the knot in October 2004, the month after the first episode aired.
Speaking at a press meeting for his new show Intelligence in January, he revealed he was having concerns about bonding with his second-born as much as his eldest.
"I was not prepared for how much love I would have in me," he said about the first time around. "So I'm a little worried, like how can I love something as much as I love my daughter? But everyone says your love just grows, so don't be afraid of that, so that's my only thing."
After taking some time off after the final season of Lost to spend time with Yessica and Java, Josh returned to the small screen at the start of 2014.
Intelligence is a drama "centered on a high-tech intelligence operative who is enhanced with a super-computer microchip in his brain, and the director of the elite government cyber-security agency who supports him," according to IMDb.
It's quite a departure from Sawyer and that's something that drew Josh to the role.
"I definitely wanted to so something other than that character, and this was also something I grew up loving," he told E! last May.
"I grew up with three brothers and we always played spy and sneak and all these games. I grew up wanting to be James Bond or a Mission: Impossible agent.
"I was like, this is a no-brainer and also it's just a skill set I haven't gotten to use a lot. I've done martial arts for years and I have a good bit of experience with weapons and so forth… I did it on Mission: Impossible for like a blip. It just naturally attracted me, and I thought the script was really smart and current."