The star included a never-before-seen snap from their London wedding in the Instagram post.
Katharine McPhee sent a sweet birthday tribute to David Foster on Friday.
The "Scorpian" star, 35, took to Instagram to help her husband celebrate his 70th milestone with a set of eight gorgeous snaps, including a never-before-seen photo from their London wedding, which shows David waiting at the alter as Katharine makes her way down the aisle.
"I've known this man for 13 years now! What was once a working relationship became a friendship and ultimately led us here. Anyone who meets him talks about how charming he is, so much so that he eventually charmed his way into my heart," the star captioned the post.
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View Story"I'm so proud that he's my husband! May God bless you with many many more years. Happy birthday baby," she added.
The Instagram gallery also included a black-and-white throwback of a young David and pictures of the pair cozying up on the red carpet for their myriad of Tinseltown events.
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Katharine recently revealed their marriage has been one of bliss, as the two get along swimmingly.
"There's not arguing, no drama," she told Entertainment Tonight. "It's just easy, that's how it should be."
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View StoryThe couple -- who first met on set of "American Idol" in 2006 -- married at the Church of Saint Yeghiche in the South Kensington district of West London in June.
The ceremony marked the second marriage for Katharine and the fifth for David. Katharine was married to Nick Cokas previously, while David had tied the knot with B.J. Cook, Rebecca Dyer, Linda Thompson and Yolanda Hadid.
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