The episode was watched by 8.58 million households and by 14 million viewers, overall. In the United Kingdom, "Existence" premiered on June 28, 2001, and received 0.65 million viewers, placing "The X-Files" number three in the top ten broadcasts for Sky1 that week behind "" and "The Simpsons". Fox promoted the episode with the tagline "Will the beginning be the end?" The episode was later included on "The X-Files Mythology, Volume 4 – Super Soldiers", a DVD collection that contains episodes involved with the alien super soldiers arc. "Existence" received mostly positive reviews from critics. Zack Handlen of "The A.V. Club" awarded the episode a "B". While offering a positive opinion in regards to the finale as a whole, he felt that "Existence" dragged more so than "Essence", resulting in a less interesting episode. He also felt that the overarching mythology of the series had long ago become too convoluted to make sense, but that the "human pieces of the show still work, and that includes Doggett." "Contra Costa Times" columnists George Avalos and Michael Liedtke were pleased with the episode noting that the last scene was "beautifully written". Avalos and Liedtke also reacted positively to the death of Alex Krycek at the hands of Skinner, saying it was the best scene in the episode. Despite their praise, however, they stressed that "Existence" was not as exciting as the previous episode, "Essence," or the 1998 "The X-Files" feature film. Jessica Morgan of Television Without Pity gave the episode an A- rating, noting that "season eight's finale goes out with a big fat juicy kiss between Mulder and Scully, at long last". Gareth Wigmore of "TV Zone" was positive toward both "Essence" and "Existence". Wigmore gave the episodes a 9 out of 10 rating and wrote "the reason that this two-parter works is that its plot is simple enough for the audience to still have a handle on". Not all reviews were positive. Robert Shearman and Lars Pearson, in their book "Wanting to Believe: A Critical Guide to The X-Files, Millennium & The Lone Gunmen", gave the episode a more mixed two-and-a-half stars out of five. Paula Vitaris from "Cinefantastique" gave the episode a scathing review and awarded it no stars out of four.