Will Arnett is dating Carolyn Murphy

Sources told People magazine that Will and Alessandra "remain committed co-parents" to their five-year-old son Denny.

The Smartless podcaster stepped out with Carolyn - who has 24-year-old Dylan from a previous relationship - in London a few weeks ago to see Sean Hayes' play Good Night, Oscar.

Sean shared a photo on Instagram of himself, husband Scott Icenogle, Will and Carolyn backstage at the production and wrote: "Another recent surprise visit from one of the greats. Love you, Willie.[heart emoji] #GoodNightOscar (sic)"

The former Arrested Development actor also has Archie, 16, and Abel, 15, with ex-wife Amy Poehler.

The pair divorced in 2012 but remain close and Amy appeared earlier this year on Will's podcast, which he co-hosts with Sean Hayes, 54, and Jason Bateman, 56.

On the April episode, Will spoke warmly about Amy's parenting.

He said: "I have to try really hard, but Amy you're really good at this and you help me do this in concert with you, to remember to listen to what they're saying and to not try to impose what I think, 'You need this, you need that.'

"To actually sit and listen to what your kid is trying to say. Encourage them to, as much as they can, to speak. I don't come by it naturally because that's not how I was raised."

He also praised their continuing co-parenting relationship.

He said: "I am really proud of it. Of course, things take a minute because everybody is sort of adjusting to what it is.

"I'm also very proud of, certainly as parents, what we've been able to do. That has been really important to both of us. I'm really, really lucky to have her as a partner in this way.

"There aren't many people I speak to more than I speak to her, which is weird, you know what I mean. But it's great. I feel really lucky.

"She's the person that I go like, 'Hey, I'm thinking about doing this.' Whether it's life or work and I really seek her counsel because it's important to me because I trust her. She's awesome."

Will previously spoke about how fatherhood had changed him.

Speaking on the Our Way with Paul Anka and Skip Bronson podcast last year, he said: "I'm crazy about my kids. I always joked that before I had kids, I didn't notice them. I didn't have my first son until I was 38.

"Up until that point - I mean, it's a joke obviously - I was always like, 'Yeah, people have kids. Yeah, yeah, yeah, yeah'.

"And then you have kids of your own and you go, 'Wow!' It really brought everything into focus for me in life and it really put everything into perspective."