Entertainment Weeklys Eli Enis and Alex Suskind recalled "pitch-perfect harmonies" of "Leave the Door Open", placing it on the segment "Friday Five" on March 5, 2021. The song was also included on Under the Radar Songs of the Week on March 5, 2021; Mark Redfern said, "You can imagine many a baby being conceived to the retro-sounding track." Siroky and the Staff from Consequence considered the song the Top Song of the Week on March 6, 2021, saying it "wouldn't feel out of place on Bruno Mars'...2016 24K Magic album — why mess with a great thing, after all?" J'na Jefferson of Uproxx named the song as one of the contenders for "2021 Song Of The Summer". Jefferson dubbed the lyrics as "inviting [and] sensual". Dee Locket from Vulture included the song on her April list of The Best Songs of 2021 (So Far), saying that the song borrows from the Isley Brothers. She added, "Neither is going about musical curiosity the wrong way." Dave Holmes, in Esquires "Best Songs of 2021 (So Far)" praised "Leave the Door Open", calling it a "flawless tribute to mid-'70s R&B with a key change that will make you stand up and cheer"." The song was considered the best release until June 2021 by Complex; Jessica McKinney wrote "rarely does a new record come along that can bring together all generations, but 'Leave the Door Open' does exactly that. It has a timeless, feel-good quality with the power to unite a room full of people on a dance floor." "Leave the Door Open" was listed as one of "The 50 Best Songs of 2021" by Billboard Staff Picks on June 8, 2021.
