Michelle just shared this never-before-seen family pic ... and everyone's looking quite fashionable.

Barry O's chilling in a buttondown shirt and some khaki slacks, Sasha's glowing in a slender black dress, Malia's beaming in a lilac getup and Michelle's one proud mama. Talk about #FamilyGoals.

The Obamas sure look happy and healthy ... so Barack and co. have a lot to be thankful for this Thanksgiving.

As for the timing of the photo ... looks like it was taken back when Sasha went to her high school prom. A couple pics surfaced after the event, but this is the first we've seen of the whole fam together.