The former pop star tweeted a picture of herself looking entirely fresh-faced with her blond tresses down and wavy.
"Aquaphor from the diaper bag...And a filter ;) Date night!" she captioned the picture.
Aquaphor is a petroleum jelly protectant that can be used on both adults and babies. After welcoming son Ace Knute in June 2013, Simpson, 33, has been slimming down and enjoying time with her growing family.
The foursome spent Thanksgiving in Boston with Johnson's family, and Simpson and her NFL star fiance are currently planning their long-awaited nuptials. In October 2013, they were spotted scouting wedding venues in Capri.
And following the birth of Ace, Simpson has been slimming down thanks to her deal with Weight Watchers.
"With a toddler on the run and an infant to look after I knew I needed a plan that's simple and fits into my life," she told Tumblr's MomFeeds in November 2013. "I know Weight Watchers works, so I got on the plan again."
Click on for photos of more stars without makeup...