The "Fuller House" star, 55, took to Instagram on Sunday with a wedding photo of the pair sharing a kiss as husband and wife.
"... and our fairytale has only just begun. Happy Anniversary my love," the actor gushed in the caption.
Stamos began dating McHugh nearly three years ago. The couple announced their engagement in October 2017, and followed that up in December 2017 with an announcement that they were expecting their first child.
"From now on, the best part of me will always be my wife and my son,'' Stamos wrote next to the first pic of Billy he shared with his fans.
The "Scream Queens" alum isn't the only one feeling grateful. His wife also celebrated their big day with a heartfelt tribute.
The 32-year-old actress, writer and model shared her own wedding-day pic of the pair smooching, and in her caption she opened up about their whirlwind first year of matrimony.
"One year ago today we read Disney-themed vows to each other in front of some of our most cherished friends and family members," McHugh wrote.
"Year one kept us busy — becoming new parents — lots of constant change, and changing diapers!" she continued. "But one thing hasn't changed, prioritizing our relationship. Knowing that if we work on keeping us strong all is good. Thank you for prioritizing us."
She added, "Excited for you to come home so we can celebrate together."
Happy anniversary, John and Caitlin!