"Happy 30th birthday to this absolute gem," wrote the Goop founder on Friday, alongside an adorable black-and-white photo of Johnson on her Instagram page.
Johnson has been dating Paltrow's ex-husband, Chris Martin, since October 2017. Paltrow and Martin originally separated in 2014, in a process that they described as "consciously uncoupling." However, Paltrow has been loving and respectful towards Johnson, and gone out of her way to include her, according to reports.
Johnson has yet to respond to Paltrow's Instagram post publicly, but fans were quick to praise Paltrow's sweet message.
"And THIS is how family behaves!" wrote one user.
"It's so lovely that you all get along," added another.
They all get along so great, that when Paltrow and her new husband Brad Falchuk celebrated their wedding with a family honeymoon to the Maldives last year, Martin joined.
Paltrow told The Sunday Times of their relationship, "Chris is family, and Brad and he, they're like, totally friends."