On Sunday, the Tron: Legacy actor shared a picture to Instagram of a handwritten note he wrote to Roberts, 31, on the special day.
"Happy Mother's Day! To the most beautiful mother, dear Emma!" the letter began. "You gave us a gift who never ceases to melt our hearts, amaze our minds, and make all the anythings just fly away, from morning till night."
"All my love," he concluded.
In a second post, Hedlund, 37, shared another sweet note written on behalf of his 16-month-old son Rhodes, whom he shares with the American Horror Story actress.
"Happy Mother's Day! To my dearest mama!" the message read. "I love you with all my heart, forever, and again! Here's to lookin' at the moon!"
The letter concluded with a heart-shaped signature and the words: "All my heart, your son."
In January, PEOPLE confirmed that Roberts and Hedlund broke things off following a rocky few months in their relationship.
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A source told PEOPLE at the time that Roberts and Hedlund are "trying their best to co-parent" though "it's been hard."
The pair, who started dating in March 2019, celebrated their son Rhodes' 1st birthday in December 2021. "I love you Rhodes," Roberts wrote in a birthday tribute to their son at the time.
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In March, Hedlund shared a sweet photo from a zoo trip with Rhodes on his Instagram Story. In the shot, Hedlund can be seen holding his little boy on his hip as the two stood behind a fence to admire flamingos.
"Me and my best buddy @thezoo," Hedlund captioned the photo.