"In every scene, you are my star, @MichelleObama! Happy birthday, baby!" the former president wrote in a tweet. He accompanied the message with four black-and-white photo booth-style shots of the couple hugging and kissing.
Within a matter of hours, Obama's tweet had earned more than 1 million likes and 150,000 retweets.
The former first lady, born on Jan. 17, 1964, is celebrating her 56th birthday.
Obama's birthday comes just weeks after she was named the "most admired woman" in the world for the second year in a row in a Gallup poll.
The former first lady, a mom of two, is also gearing up for the Grammy Awards later this month. She is nominated in the best spoken word category for the audio version of her best-selling memoir, "Becoming."
ABC News contributed to this report.