The couple welcomed baby Rhodes in December 2020, and on Friday, February 19, the new dad revealed the family now has a special link to McGraw, Garrett's co-star in 2004's "Friday Night Lights" and 2010's "Country Strong".
"He's somebody that I admire and respect, not only as an amazing father and an amazing husband, amazing musician and amazing actor (sic)...," Garrett shared on "The Kelly Clarkson Show". "I've known him for a long time."
"We laugh about it because it's probably been over 17 years since we did Friday Night Lights together, we played father and son," he continued.
"So I got to first experience him as a father - in that film, somewhat more of an abusive one - but then we did Country Strong together, and we've remained such close friends and, you know, I've seen his children, his daughters, from the time they were one, three, and five."
Tim shares his girls, Gracie, 23, Maggie, 22, and Audrey, 19, with his wife and fellow singer Faith Hill, and Garrett confesses the country music veteran was the one to volunteer his services.
"He's the best," Garrett gushed. "After around 12 weeks of Emma being pregnant, I called him, and the first thing he said was, 'I'm the godfather.' So, how can you argue?"
Little Rhodes is the first child for both Garrett and Emma, who began dating in 2019. The "Scream Queens" alum confirmed her pregnancy in August 2020.