Adams, 51, is known for his songs "Summer of '69," "Heaven," "Cuts Like a Knife," "Run to You," "[Everything I Do] I Do It For You," "Straight From the Heart," "Please Forgive Me" and "All For Love."
"She helped me start my foundation years ago and it looks like she'll be running the family now!" UsMagazine.com reported Adams said on his Web site. "Thanks for your support and kind messages, we appreciate it greatly."
There was no word regarding how long Adams and Grimaldi have been a couple or when their baby is due.