The actor has recently defended his wife amid her ongoing heritage scandal.
The sweet shot featured the couple sitting on their porch with their five kids -- Carmen, 7, Rafael, 5, Leonardo, 4, Romeo, 2, and Eduardo, four months.
"Happy birthday to the love of my life," Alec wrote. "To the only person in the world who brings me joy and peace every day. The person who is my home. My everything."
Hilaria's birthday comes amid an ongoing controversy surrounding her heritage. Recent social media posts claim that the mom of five exaggerated her connection to Spain after it came to light that she was not born there, but rather in Boston. Additionally, her given name at birth was not Hilaria, but Hillary Hayward-Thomas.
"Alec has always known that Hilaria is from Boston," the source said. "... They are focused on taking care of their small five children and being there for each other as a family."