Vanessa took to Instagram on Monday to share a snapshot from the b-day bash, showing off her and her son's custom shirts -- featuring Superman's logo, but with a 'C' in place of the traditional 'S' -- and his incredible, three-tiered superhero cake!
"#HappyBirthday sweet angel boy! May ALL your wishes come true!" the proud mom captioned the cute photo of her son blowing out his candles. "We LOVE you sooooooooo much! #CamdenJohnLachey #SuperCam."
The 98 Degrees singer also shared a tribute to his young son on Instagram, posting a heartwarming throwback pic of Camden as a baby, smiling in his father's arms.
"Four years ago, this little angel came into our lives and every day has been better because of him!!" Nick wrote alongside the beaming snapshot. "Happy Birthday Camden John. We love you!!"
Nick, 42, and Vanessa, 35, who tied the knot in 2011 in a ceremony on Richard Branson's private island in the British Virgin Islands, welcomed Camden on Sept. 12, 2012. The couple also share a 1-year-old daughter, Brooklyn Elisabeth.
Earlier this month, the pair announced that they were expecting their third child. Check out the video below for a look at the excited parents' adorable pregnancy announcement!