That honour was previously held by Toy Story 2.
Lady Bird's coming of age is not new to cinema, yet Gerwig's version is light, fresh and modern, despite being set in 2002.
The 100% list is so inconsistent that Rotten Tomatoes has its own "Best of RT" list that weighs the number of film reviews with the score, resulting in many films with a (gasp) lower-than-100% score to lead the ranking - aka, The Wizard of Oz at a mere 99%.
The 23-year-old nabbed the Best Actress gong at the Independent Filmmaker Project's 27th Annual Gotham Independent Film Awards in NY. The more positive "fresh" reviews from critics, the higher a film's Rotten Tomato rating will be.
This is completely fantastic and so incredibly appreciated by the entire team that made Lady Bird, she tells Rotten Tomatoes. Still, even with all those positive reviews, its overall rating was 8.3 out of 10.
"This is completely awesome and so incredibly appreciated by the entire team that made Lady Bird", Gerwig said exclusively to RT, "We put our heart and souls into this movie, and the last step of this deeply collaborative art form of filmmaking is giving the film to the audience and the film critics".
She added, "We are all on cloud nine and using our tomato emoji more than we ever thought possible".
In the case of Gerwig's Lady Bird, it was given a wide release and thus had to adhere to that higher standard, which it leapt over with grace.
So what is Lady Bird?