The KISS rocker and his daughter, Sophie Simmons, went with "Can't Help Falling In Love" for the first song of their father-daughter dance ... and it's a super sweet moment.

Gene and Sophie share a few words as they show off their ballroom dancing skills, it's clear he's one proud papa.

The wedding reception was Thursday at Delilah in West Hollywood ... and as you can see, it was a speakeasy theme, with tons of gold balloons and most guests wearing black and white.

We're told Jeff Ross was among the celebs in attendance.

The day before the reception, Gene's daughter got hitched to James Henderson in an intimate ceremony Wednesday, exchanging vows in Malibu.

We also obtained video of Sophie getting on the mic and singing during the party, which raged on well into the night. Remember, she's a singer herself.