Halle Bailey and DDG Celebrate Son Halo's First Birthday

Halle Bailey and her ex, DDG, got together to celebrate their son Halo's first trip around the sun ... and the celeb parents went all out for his birthday bash.

The "Little Mermaid" singer shared photos and videos from Sunday's birthday party on her social media ... smiling and holding Halo.

The party had a "Cocomelon" theme ... there was a ball pit, a couple slides, and a ton of balloons ... plus a cool Cocomelon cake for Halo.

Halle even shared video of her singing "Happy Birthday" to her only child ... belting out the lyrics while fighting back tears.

Emotional day watching her baby turn 1, because Halle says ... "I cried so much yesterday."

Halle reunited with her ex, DDG, too ... and they even snapped some photos together as a family of three ... with Halo in the middle, flanked by his parents.

As we reported ... DDG announced their split back in October, when the rapper said they would co-parent Halo.

It looks like the co-parenting thing is going well, at least based off this snippet from the party.