The singer can't wait to start a family with the TV host as she knows how great he would be with any children they had.
She said: "He'd be the best dad in the whole world!"
Mariah and Nick - who wed last year following a whirlwind romance – were at the UNICEF Snowflake Ball and the 'Hero' star says the wellbeing of all children is one of her main priorities in life.
She said: "We have to take care of children. Any time I can be a part of helping out, I'm here."
Mariah, 40, recently revealed she feels "complete" since marrying Nick.
The singer - who was previously married to record company boss Tommy Mottola - said: "People were surprised when we got married but it felt like the right thing to do and it wasn't anything out of the ordinary for us.
"I definitely feel more complete than before. There's a void you have when you don't feel you've found the other part of who you are, so I'm in a different place now and that's nice to experience.
"I think being able to collaborate with Nick and being in a really great place in my life is having a great impact on my music."