The Younger actress, 28, and the hockey player, 35, did some Black Friday shopping with their little boy at The Grove in LA, reported Us magazine.
On Thanksgiving, the former "Lizzie McGuire" star took to Instagram to express her gratitude for Luca.
"#thankful everyday," she captioned a photo of her son.
Duff and Comrie - who also reunited for Luca's third birthday in March - split in January after four years of marriage.