Katharine McPhee welcomed her first baby, son Rennie David, with husband David Foster on Feb. 22

New mom Katharine McPhee has a whole lot to celebrate this Mother's Day.

On Sunday, the Country Comfort star, 37, enjoyed her first Mother's Day as a mom after welcoming son Rennie David with husband David Foster last February.

McPhee, who wed Foster in June 2019, commemorated the occasion by wearing a sweatshirt from BFFS & Babes that featured her baby boy's name written in a heart.

The star posted a selfie to her Instagram Story while wearing the bright blue crewneck with Rennie's name centered in the upper left corner in a white heart.

The singer's stepdaughter Sara Foster also honored McPhee on social media as the new mom celebrated the milestone holiday.

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Credit: katherine foster/ instagram
katherine foster
Credit: katherine foster/ instagram

Foster posted a snap with McPhee and sister Erin too, writing, "Happy first mamas day to Rennie's mom @katharinefoster"

Rennie is the first child for McPhee and the sixth for Foster, 71, who has five daughters from previous relationships.

Last week, the American Idol alumna appeared on the PEOPLE Every Day podcast where she opened up about her experience parenting with Foster.

"It's a growing family, and David's doing great," McPhee said. "He's always walking into a room saying, 'Where's my baby? Where's our baby?' He wants to hold the baby all the time, and be around the baby."

As for McPhee, the actress is loving every minute of motherhood.

RELATED VIDEO: It's a Boy! Katharine McPhee and Husband David Foster Welcome a Son

The Smash star appeared on The Kelly Clarkson Show last month where she shared that being a mom is the "greatest job" she will ever have.

Asked by host Kelly Clarkson if she is tired after welcoming her son, McPhee said, "I'm a little bit tired here and there but I find times to nap," before she added, "He's such a good little baby and I'm so in love ... It's my greatest job I'll ever have."

McPhee welcomed her first child with Foster on Feb. 22, her rep confirmed to PEOPLE exclusively at the time.

"Katharine McPhee and David Foster have welcomed a healthy baby boy," the rep told PEOPLE at the time. "Mom, Dad and son are all doing wonderfully."